WASHINGTON -- On Nov. 15, a week after Democrats saw sweeping wins in U.S. Senate races, MoveOn.org members received an email from one of the biggest victors.

"I still can't believe it, even as I'm writing it. I'm in Washington, D.C. right now for the Senate's freshman orientation!" wrote Elizabeth Warren. "They have some strict rules around here, and I don't want to get caught passing notes. But I had to take a quick moment to say: THANK YOU."

Warren certainly had plenty for which to thank the progressive community. MoveOn alone raised more than $1 million for the Massachusetts Democratic Senate candidate. And instead of having one of her staffers write the email, she wrote it herself.

"Obviously Elizabeth is above writing emails, but she doesn't think of herself as above writing emails," said Daniel Mintz, who was MoveOn's national director of coordinated campaigns at the time. "I think that speaks to how Elizabeth views digital and online organizing herself -- as a means by which she can connect to this broader movement. I think she very much sees herself -- not just as the senator from Massachusetts ... but as a leader of, and part of, this broader movement."

Warren's digital operation was one of her secret weapons in her race against Scott Brown, the Republican incumbent. She built up one of the most sophisticated programs outside of the presidential campaigns, bringing on Lauren Miller -- a respected strategist from Blue State Digital -- as a full-time senior staffer devoted to new media. That digital army has the potential to be a tremendous asset to Warren in the Senate; the challenge, however, comes in keeping that list of supporters engaged when there's no campaign going on.

The Warren campaign essentially ran two different digital programs simultaneously: One was targeted at Massachusetts voters, who could knock on doors, phone-bank and ultimately, vote for Warren. The other was aimed at supporters around the country, who could build enthusiasm and donate, but not actually cast a ballot.

Mintz said that such a strategy isn't unique, but it takes a certain level of "sophistication and resources" that few campaigns possess.

"The campaign made a decision early on that digital could be a real resource for them, and so it was not something that they just shunned to the side or treated solely as a piggy bank," he said. "It also wasn't something where they said, we'll just hire a consultant and have them run it. They really wanted it to be integrated in the campaign, and I think they did that well."

The campaign did hire the consulting group Bully Pulpit Interactive, which also worked on President Barack Obama's reelection effort, to run its ad program. Miller said while it's smart to run an email operation in-house, running an ad program is beyond the capabilities of any Senate or House campaign.

BPI Partner Mark Skidmore was the chief digital ad strategist for the Warren campaign. He had three goals: persuasion (convincing voters to lean toward Warren), mobilization (get out the vote) and acquisition (donations). Reaching out to supporters on Facebook ended up being more important than he had anticipated -- it was virtually a non-issue in the 2008 election -- and the best times were during key moments in the campaign.

"From a buying perspective, early on, we really concentrated on the key moments we wanted to own. I think that was a really important part of the campaign," Skidmore said. "I would have spent way more on the conventions, for instance, because we saw a huge return from ads around the convention. Same thing around the debates -- I don't think we could have forecasted she would have done so well in those debates, but if I could have looked back and planned those out, we would have bought those debate moments even bigger than we had."

The gender gap also played a significant role in the Massachusetts race, with women heavily favoring Warren and men going for Brown. That made the digital strategy especially important for Warren's campaign, since women dominate many social media sites.

Warren's savvy digital operation also made it easier for outside organizations to mobilize grassroots support on her behalf. The Progressive Change Campaign Committee was one of Warren's earliest -- and strongest -- backers, raising more than a million dollars for her campaign. In July 2011, it launched a "Draft Warren" campaign to encourage her to run for Massachusetts' Senate seat, bringing in $100,000 for her before she had even announced. Warren recorded a "thank you" video that was sent to PCCC's supporters after the campaign.

"Elizabeth Warren's online operation had three major things working for it: Elizabeth's reputation for being a bold fighter that preceded her candidacy, Elizabeth's authenticity and a very sophisticated online operation that included a network of national progressive allies," said PCCC co-founder Adam Green.

A big question for the Warren campaign now is what to do with its digital operation now that she is in the Senate. Miller -- who is now on Warren's Senate staff -- told The Huffington Post that they are still figuring out what the post-campaign digital operation will look like, and how they will keep her supporters engaged. Warren already started a political action committee and helped raise money for Sen. Al Franken's (D-Minn.) reelection effort.

"During her entire campaign, she said we're going to fight every day until Election Day, and here's the really important part, we're going to keep fighting every day after the election to bring about change for middle-class families. ... Certainly we're not shutting down the program anytime soon, especially for the next six months," Miller said. "She cared the entire campaign about giving people a voice, about talking about investments in education and infrastructure and research, and she wants to keep giving people that voice."

Keeping up a strong digital operation is trickier while in office. Obama and Organizing for America, for example, came under significant heat from progressives for not staying as engaged during the big policy fights, such as health care reform. But figuring out that equation could be enormously powerful. MoveOn, for instance, has wielded significant influence on Capitol Hill amongst Democratic lawmakers, who know the group can help them raise money from their massive email list -- or launch a campaign to pressure them if they veer toward the right.

"It's more difficult to be an elected [official] in control of a big list of people than it is to be an outside organization. There are more strictures on what you can and can't do and the propriety of doing certain things," said Mintz, noting that some lawmakers are reluctant to go after members of their own party who may be the ones actually blocking legislation.

Miller declined to reveal the number of individuals on Warren's email list, but she said she's "never seen an email list of people more willing to give."

"I don't think the nut has been cracked yet, but I do think there are a number of people working hard at it, and I'm sure that Elizabeth will join that group," Mintz added. "I expect that they're going to trailblaze new ways for elected officials for mobilize their own lists and work with outside groups directly on an inside-outside game that you can show people in D.C. how much pressure there is outside D.C. for the kinds of changes that we want to see."

This story has been updated to include comments from the Progressive Change Campaign Committee.

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  • Hillary Rodham Clinton

    Clinton certainly has the resume to be a strong presidential contender: two terms as the first lady during her husband's popular administration, eight years as a U.S. senator from New York and four as a widely-acclaimed secretary of state under President Barack Obama. Not to mention that she has already mounted a presidential bid once before, during the 2008 Democratic primary. With quite a following among Democrats -- particularly women -- and an expert campaigner as a husband, Clinton is one of the frontrunners for the 2016 nomination. In fact, if the Iowa caucuses were held today, a <a href="http://www.politico.com/blogs/burns-haberman/2012/11/exclusive-clinton-would-dominate-iowa-caucuses-ppp-149064.html">Public Policy Polling survey</a> found she would win 58 percent of the vote, outstripping the runner-up, Vice President Joe Biden, by a margin of 41 percent. Now the question is <a href="http://www.nytimes.com/2012/11/11/opinion/sunday/collins-hillarys-next-move.html?_r=0" target="_blank">whether or not Clinton will decide</a> to throw her hat in the ring in 2016. After her term as secretary of state ends this year, she has declared her intention to take a year off from politics entirely. And after that? Clinton says that she <a href="http://politicalticker.blogs.cnn.com/2012/10/18/hillary-clinton-repeats-no-2016-cant-stand-whinin-about-life-choices/">does not want to run</a> in 2016, but that hasn't quashed hopes to the contrary. <em>-- Sarah Bufkin</em>

  • Susana Martinez

    Susana Martinez, a Republican, was elected in 2010, becoming the first female governor of New Mexico and first female Hispanic governor in the United States. Her name was also floated as a potential running mate to Mitt Romney in 2012, but she was ultimately passed over for the job. The GOP's poor showing among women and Latinos in this year's presidential election, however, could make Martinez a strong potential choice in 2016. <em>-- Sarafina Wright</em>

  • Elizabeth Warren

    Warren, a favorite of many liberals and a fierce advocate of financial reform, beat out Sen. Scott Brown (R-Mass.) in their 2012 contest, putting a Democrat back in the seat formerly held by the late Ted Kennedy. Warren first made a name for herself on the political scene after Senate Majority Leader Harry Reid (D-Nev.) tapped her to chair the congressional panel tasked with overseeing the distribution of the stimulus funds. A bankruptcy law expert and professor at Harvard Law School, Warren pushed for the creation of the Consumer Financial Protection Bureau and later led the effort to set up the new agency. After Republicans made it clear that they would never confirm Warren as the new CFPB head, the president passed her over in favor of Ohio Attorney General Richard Cordray. In 2011, Warren declared her intention to challenge Brown for his seat. She proved to be one of the most magnetic Senate candidates, raising $39 million for her campaign and giving a primetime speech at the Democratic National Convention. Although immensely popular with Democrats, Warren <a href="http://abcnews.go.com/blogs/politics/2012/10/elizabeth-warren-2016/">has denied</a> that she would consider a presidential run in 2016. <em>-- Sarah Bufkin</em>

  • Kelly Ayotte

    As one of Mitt Romney's top surrogates during the 2012 presidential campaign, Sen. Kelly Ayotte (R-N.H.) gained national exposure, regularly appearing on cable TV and the Sunday show circuit. Before her successful Senate election in 2010, she served as New Hampshire's attorney general. A strong conservative <a href="http://www.washingtonpost.com/blogs/2chambers/wp/2012/11/14/no-love-for-susan-rice-from-john-mccain-lindsey-graham-and-kelly-ayotte/">quickly building her profile in the Senate</a>, Ayotte could answer the call to help Republicans win back the support of women. <em>-- Sarafina Wright</em>

  • Kirsten Gillibrand

    A progressive Democratic senator from New York, Gillibrand recently <a href="http://www.buffalonews.com/apps/pbcs.dll/article?AID=/20121113/WORLD/121119739/1003">won reelection</a> with 72 percent of the vote in 2012, the highest margin of any senator in the state's history. After serving as special counsel to Andrew Cuomo during his tenure as the secretary of housing and urban development in the Clinton administration, the former attorney worked on Hillary Clinton's successful campaign for Senate in 2000. She <a href="http://nymag.com/news/politics/57197/">credits Clinton</a> with inspiring her to get into politics, and in 2006, Gillibrand won a House seat in the district that included her hometown of Albany, N.Y. Two years later, when her former mentor left to become the secretary of state, Gov. David Paterson appointed Gillibrand to fill Clinton's former Senate seat. Gillibrand <a href="http://www.capitalnewyork.com/article/politics/2010/12/983717/what-dont-ask-dont-tell-did-kirsten-gillibrand">lobbied successfully</a> for the repeal of the "don't ask, don't tell" policy and led a campaign to get more women elected to Congress. <em>-- Sarah Bufkin</em>

  • Cathy McMorris Rodgers

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  • Condoleezza Rice

    The first African-American woman to serve as secretary of state would certainly be a trailblazer if she ran for president and became the first female commander-in-chief. A Republican, Rice is an accomplished pianist, holds a Ph.D in political science and has served as provost of Stanford University. She served as President George W. Bush's first national security adviser before moving to the State Department. Though she has never run for elected office, she was a popular choice to be Mitt Romney's vice presidential pick, due to her foreign policy credentials and ability to bridge the GOP's gap with women and non-white voters. <em><strong>Correction:</strong> An earlier version of this text misstated that Rice was the first African-American secretary of state. She was the first African-American woman to serve in that position.</em> <em>-- Daniel Lippman</em>

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  • Nikki Haley

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  • Maggie Hassan

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  • Jennifer Granholm

    Granholm, the feisty former Democratic governor of Michigan, is now the host of The War Room television show on Current TV. Born in Canada, she became the first female governor of her state in 2003 and served until 2011, championing the critically important auto sector during a period of intense challenges. She <a href="http://www.huffingtonpost.com/2012/09/06/jennifer-granholm-speech-democratic-convention_n_1863181.html">reminded voters of her passionate nature</a> at the 2012 Democratic National Convention, where she delivered an animated address. A graduate of the University of California, Berkeley and Harvard Law School, Granholm served as her state's attorney general before being elected governor. She has three children. While Granholm would currently be barred from running due to the Constitution's requirement that presidential candidates be natural-born, there have long been arguments about amending the language to allow for naturalized citizens to run as well. <em>This post has been updated with additional information about Granholm's birthplace and constitutional restrictions</em> <em>-- Daniel Lippman</em>

  • Sarah Palin

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  • Lisa Murkowski

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  • Christine Gregoire

    Gregoire, formerly the Democratic governor of the state of Washington, is the second female to serve in that position. A lawyer, Gregoire was elected attorney general of her state in 1992 before being elected governor in 2004 in a razor-tight race against Republican Dino Rossi. She was reelected in 2008 and also served as the chairwoman of the National Governors Association for the 2010-11 term. One of her top accomplishments as governor included a plan to raise revenue to fund new transportation improvements to fix roads in Washington. She is a supporter of gay marriage, which was passed in her state in 2012. <em>-- Daniel Lippman</em> <em>This slide was first published before the 2012 elections and has been updated to reflect that Gregoire left office in January 2013.</em>

  • Michele Bachmann

    The Republican Tea Party favorite from Minnesota has already attempted a run at the White House and failed to clear the hurdles of the GOP primary, but she could be up to give it another go. Bachmann is an outspoken conservative who stands with the right-wing segment of the party. She opposes tax increases, big-government spending, the Affordable Care Act, environmental regulation and gay rights. The four-term congresswoman is an <a href="http://www.washingtonpost.com/politics/michele-bachmann-others-raise-millions-for-political-campaigns-with-money-blurts/2011/06/16/AGROkubH_story.html">adroit fundraiser</a>, employing a strategy that allows her to make controversial statements on public platforms and then reap the funding windfall. In 2008, she brought in nearly $1 million after accusing President Barack Obama of having anti-American views. But the Minnesotan barely clung on to her seat in the 2012 election, eeking out a win by just over 4,000 votes -- which calls into question her ability to attract the majority of the GOP electorate and independent voters four years from now. <em>-- Sarah Bufkin</em>

  • Kristi Noem

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  • Pam Bondi

    As Florida's Republican attorney general, Pam Bondi was a leader in the failed effort to overturn President Barack Obama's signature legislative achievement, the Affordable Care Act. At the 2012 Republican National Convention in Tampa, Fla., Bondi drew attention for her assertion that Obama has a "total disregard for our individual liberty." Given her status as a female public figure serving in a swing state, who has worked to achieve one of the GOP's core goals (repealing Obamacare), expect to hear Bondi's name more in the years to come. <em>-- Ian Gray</em>