WASHINGTON -- Democrats have entered the go-for-the-jugular stage of the presidential race, with President Barack Obama's campaign, the Democratic National Committee and an allied opposition research group all releasing videos Tuesday attacking Mitt Romney for his refusal to release more tax returns.

The videos are distinct. The Obama campaign clip will air on television in Pennsylvania, where Mitt Romney is campaigning today. The DNC's version craftily uses Sarah Palin to suggest that John McCain was so nervous about Romney's taxes that he made a historic roll of the dice with his running mate pick in 2008. The video put together by American Bridge 21st Century is a sharp edit job of clips of all the prominent GOP officials and pundits who have begun groaning about Romney's handling of the matter.

All three videos hit at the same theme: Romney's obstinacy on tax returns has become a crippling problem for his campaign and one that Democrats are intent on compounding. Romney has released his completed return for 2010 and his estimated return for 2011, showing an effective 2010 tax rate of 13.9 percent and financial accounts in Switzerland, Bermuda and the Cayman Islands.

"Until he releases additional years of tax returns, the American people won't know why he kept his finances offshore in the Cayman Islands and set up a shell corporation in Bermuda," emailed Ben LaBolt, Obama's campaign press secretary. "Romney would be the first nominee in decades to release only one full year of tax returns. He recently said that his campaign has “put out as much as we’re going to put out” -– which makes you wonder: What is Mitt Romney hiding?"

The use of Palin by the DNC seems designed specifically to get the web video some cable news attention and free publicity. But the suggestion that the 23 years of tax returns that Romney provided to McCain campaign doomed his prospects as a potential 2008 VP pick was disputed by the Arizona Republican's campaign manager, Steve Schmidt.

WATCH THE OBAMA CAMPAIGN VIDEO

WATCH THE DNC VIDEO

WATCH THE AMERICAN BRIDGE VIDEO

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  • Birth Certificate -- "Born In The USA"

    <a href="http://www.huffingtonpost.com/2011/04/27/obama-birth-certificate-r_n_854248.html" target="_hplink"><strong>(April 27, 2011) --</strong></a> The White House <a href="http://www.whitehouse.gov/blog/2011/04/27/president-obamas-long-form-birth-certificate" target="_hplink">released</a> President Barack Obama's "long form" birth certificate, adding documentation to a longstanding discussion over his ability to serve as commander in chief. "We do not have time for this kind of silliness," Obama said. "We have better stuff to do. I have got better stuff to do. We have got big problems to solve." (JEWEL SAMAD/AFP/Getty Images)

  • Osama Bin Laden Killed -- "Tonight, Tonight"

    <a href="http://www.huffingtonpost.com/2011/05/01/osama-bin-laden-dead-killed_n_856091.html" target="_hplink"><strong>(May 1, 2011)</strong></a> -- In a televised address to the nation, Obama announces that Osama bin Laden is dead. His death was the result of a U.S. operation launched today in Abbottabad, Pakistan, against a compound where bin Laden was believed to be hiding. "[T]oday's achievement is a testament to the greatness of our country and the determination of the American people," Obama proclaimed. (Photo by Pete Souza/The White House via Getty Images)

  • Debt Ceiling Deal -- "Gold On The Ceiling"

    <a href="http://www.huffingtonpost.com/2011/08/02/obama-debt-ceiling-deal-jobs_n_916285.html" target="_hplink"><strong>(Aug. 2, 2011) --</strong></a> After the Senate passed a bill to raise the debt limit, Obama pleaded with Congress to shift their attention to jobs. "I will urge them to immediately take some steps -- bipartisan, common-sense steps -- that will make a difference; that will create a climate where businesses can hire, where folks have more money in their pockets to spend, where people who are out of work can find good jobs," he said. (Photo by Brendan Smialowski/Getty Images)

  • Don't Ask Don't Tell -- "Don't Stop Believin'"

    <a href="http://www.huffingtonpost.com/2011/09/20/barack-obama-dont-ask-dont-tell-repeal-statement_n_971662.html" target="_hplink"><strong>(Sept. 20, 2011) --</strong></a> As the ban on gays serving in the military came to an end, Obama hailed the fresh start, celebrating the fact that "patriotic Americans in uniform will no longer have to lie about who they are in order to serve the country they love." (Photo by Brendan Hoffman/Getty Images)

  • Iraq War To End -- "Homeward Bound"

    <a href="http://www.huffingtonpost.com/2011/10/21/obama-iraq-troop-withdrawal_n_1024108.html" target="_hplink"><strong>(Oct. 21, 2011) --</strong></a> Obama announced that all U.S. troops will be out of Iraq by 2011, fulfilling a promise that dated back to his campaign. "As a candidate for president, I pledged to bring the war in Iraq to a responsible end," Obama said. "So today I can report that, as promised, the rest of our troops in Iraq will come home by the end of the year." (Photo credit should read JIM WATSON/AFP/Getty Images)

  • Singing Al Green's "Let's Stay Together"

    <a href="http://www.huffingtonpost.com/2012/01/20/obama-al-green-apollo-theater_n_1218070.html" target="_hplink"><strong>(Jan. 20, 2012) --</strong></a> During a fundraiser at Harlem's historic Apollo Theater, Obama delivered a memorable musical message to his donors. With Rev. Al Green in attendance, Obama sang part of Green's hit song "Let's Stay Together," drawing strong applause from the crowd.

  • Singing Robert Johnson's "Sweet Home Chicago"

    <a href="http://www.huffingtonpost.com/2012/02/21/obama-sings-sweet-home-chicago_n_1292576.html" target="_hplink"><strong>(Feb. 21, 2012) --</strong></a> Days after his Al Green rendition, Obama flexed his vocal chords again with a hometown favorite. The East Room of the White House had its blues fix filled when the president started swinging "Sweet Home Chicago."

  • Gay Marriage -- "Can't Fight This Feeling"

    <a href="http://www.huffingtonpost.com/2012/05/09/obama-gay-marriage_n_1503245.html" target="_hplink"><strong>(May 9, 2012) --</strong></a> In a sit-down interview with ABC's Robin Roberts, Obama explained his evolution on the issue, affirming his support for gay marriage. "[A]t a certain point I've just concluded that for me personally it is important for me to go ahead and affirm that I think same sex couples should be able to get married," he said.

  • Immigration -- "With Arms Wide Open"

    <a href="http://www.huffingtonpost.com/2012/06/15/obama-immigration-order-deportation-dream-act_n_1599658.html " target="_hplink"><strong>(June 15, 2012) --</strong></a> The Obama administration addressed America's immigration issue, announcing that it will halt deportations and grant work permits to young individuals eligible for Dream-Act benefits. "They pledge allegiance to our flag," Obama said. "They are Americans in their hearts, in their minds, in every single way but one: on paper."(Photo by Alex Wong/Getty Images)

  • Health Care Reform -- "Beautiful Day"

    <a href="http://www.huffingtonpost.com/2012/06/28/supreme-court-health-care-decision_n_1585131.html" target="_hplink"><strong>(June 28, 2012) --</strong></a> After weeks of speculation that Obama's signature piece of legislation could be overturned, the Supreme Court ruled that the Affordable Care Act's individual mandate is constitutional. "It should be pretty clear that I didn't do this because it's good politics," <a href="http://www.huffingtonpost.com/2012/06/28/obama-health-care-ruling_n_1632953.html" target="_hplink">Obama said</a>. "I did it because it's good for the country." (Photo by Alex Wong/Getty Images)