MIAMI BEACH, Fla. — President Barack Obama and Vice President Joe Biden unleashed a back-to-back assault Tuesday on Republican challenger Mitt Romney, re-emphasizing Democratic assertions that Romney as a venture capitalist sent U.S. jobs overseas and paid no heed to the impact on American workers.

"You've got to give Mitt Romney credit," Biden said while campaigning in Iowa. "He's a job creator in Singapore, China, India."

Obama, who was holding fundraisers in Atlanta and Miami, cast his Republican rival as the type of wealthy investor whose only goal was making money no matter the cost.

"Governor Romney and his allies believe that we should go back to the top-down economics of the last decade. They believe that if we eliminate regulations and we cut taxes by trillions of dollars, we just leave the market alone, that everybody will prosper," Obama said in Miami Beach. "They argue that if you help corporations and wealthy investors maximize their profits by whatever means necessary, whether it be layoffs or outsourcing, union busting or whatever means are available, that will automatically translate into jobs and prosperity to benefit everybody."

Behind the criticism of Romney's business record is the Obama campaign's belief that the effort to undermine a potential Romney strength – his experience as the successful head of the private equity firm Bain Capital – is yielding results and raising questions with voters.

Biden made note of news reports that Bain took over firms that sent jobs to China and India and opposed union efforts to increase wages and improve benefits. The Romney campaign has argued that the reports aren't accurate and don't take into account how work done overseas supports U.S. exports.

"The president and I don't see American workers as part of the problem. We see them as the heart of the solution," he said.

Romney campaign spokeswoman Andrea Saul called Biden's comments misleading and said they were an effort to distract voters from Obama's "disastrous economic record."

"President Obama has failed to meet his own standard for lowering unemployment because he has no idea what it takes to get our economy moving again," Saul said in a statement. "On Day One, Mitt Romney will take action to jumpstart our economy and give job creators the incentives they need to thrive here in America."

The back and forth on Romney's business record has become a familiar campaign theme. A political committee supporting Obama began airing an ad over the weekend accusing Romney of making millions while shutting down an Indiana paper plant.

Biden was beginning a two-day visit to Iowa, a swing state whose six electoral votes could be significant in the November election. He spoke to more than 400 people, many of them union members from a John Deere factory, transit workers and members of a public employees union.

For Obama, it was the second day of targeting Romney. He emphasized that their contest is a choice between ideologies, not a referendum on his own performance.

"The question is not whether we need to put more folks back to work or whether we need to see the economy growing faster or whether we need to bring down our debt," he told the crowd of donors in Atlanta. "The question is how do we do it."

The president held two fundraisers in Atlanta, followed by two events in Miami Beach, including a performance by singer Marc Anthony, raising at least $2.3 million.

Obama was holding the fundraisers at the start of a pivotal week for his campaign. The Supreme Court is expected to rule on his health care overhaul law on Thursday, passing judgment on the most significant piece of legislation during his presidency.

And it comes as Obama and his team have warned that Romney and his Republican allies would outspend him during the presidential campaign.

In an e-mail to supporters Tuesday, Obama bluntly stated: "I will be the first president in modern history to be outspent in his re-election campaign, if things continue as they have so far."

The urgent tone was designed to spur more giving. Until last month, Obama had been by far the leading fundraiser in the presidential contest. But Romney, after securing the nomination, has consolidated his support.

Romney raised more than $76 million last month for his presidential campaign and for the GOP, compared to $60 million for Obama and the Democrats. Obama's advisers say they expect Republican-leaning super PACs to pull in $1.2 billion before the election, posing a big-money challenge for the president. Obama has more than $100 million in his campaign account, but Democratic super PACs have struggled to raise money.

Obama has now raised the stakes, saying that even without the help of GOP-leaning super PACs, Romney could still outspend him.

"You're going to have more money spent in this election than ever before by the other side on negative ads," Obama said in Atlanta. "And their message will be simple. They'll say, the economy is bad and it's Obama's fault."

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Associated Press writer David Pitt contributed to this report from Waterloo, Iowa.

Here are some photos of Obama with celebrities
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  • George Clooney & President Obama

    Actor George Clooney leaves after he spoke to the media March 15, 2012 at the White House in Washington, DC. Clooney had meeting with President Barack Obama to discuss the current situations in Darfur, Sudan. (Photo by Alex Wong/Getty Images)

  • President Obama & Tyler Perry

    Actor and director Tyler Perry hugs US President Barack Obama during a campaign event at Tyler Perry Studios March 16, 2012 in Atlanta, Georgia. President Obama is spending the day traveling to Chicago, Illinois and Atlanta, Georgia to attend private and public campaign events. (Photo by BRENDAN SMIALOWSKI/AFP/Getty Images)

  • The Obamas & Oprah Winfrey

    US President Barack Obama and First Lady Michelle Obama chat with talk show host Oprah Winfrey during a taping of the Oprah Winfrey show April 27, 2011 at Harpo Studios in Chicago. (Photo by MANDEL NGAN/AFP/Getty Images)

  • President Obama & Magic Johnson

    In this handout image provided by the U.S. Navy, President Barack Obama is greeted on the court by NBA Hall of Fame basketball player Earvin 'Magic' Johnson and Michigan State University assistant coach Mike Garland. (Photo by Mass Communication Specialist 2nd Class James R. Evans/U.S. Navy via Getty Images)

  • Willow Smith Performs At The White House

    Willow Smith, daughter of Will Smith and Jada Pinkett Smitt, performs during the White House Easter Egg Roll on the South Lawn of the White House on April 25, 2011 in Washington, DC. (Photo by Roger L. Wollenberg-Pool/Getty Images)

  • Antonio Banderas & President Obama

    Antonio Banderas and his wife Melanie Griffith hosted a fundraising event for President Obama in October 2011. (Photo by Sean Gallup/Getty Images)

  • Tom Hanks Narrates Pro-Obama Film

    This 17-minute film released by President Obama's re-election campaign was directed by Davis Guggenheim (director of "An Inconvenient Truth") and narrated by actor Tom Hanks.

  • Gov. Mitt Romney & Jeff Foxworthy

    Republican presidential candidate, former Massachusetts Gov. Mitt Romney makes a campaign appearance with comedian Jeff Foxworthy at the Whistle Stop cafe March 12, 2012 in Mobile, Alabama. (Photo by Win McNamee/Getty Images)

  • Gov. Mitt Romney & Kid Rock

    Republican presidential candidate and former Massachusetts Gov. Mitt Romney greets musician Kid Rock during a campaign rally at the Royal Oak Theatre on February 27, 2012 in Royal Oak, Michigan. (Photo by Justin Sullivan/Getty Images)

  • David Mustaine & Rick Santorum

    David Mustaine of Megadeth expressed support for Rick Santorum in a February <a href="http://www.musicradar.com/news/live/interview-megadeths-dave-mustaine-talks-guitar-politics-and-todays-music-529703" target="_hplink">interview with Music Radar</a>.

  • Kelly Clarkson & Ron Paul

    Kelly Clarkson tweeted about her love for Ron Paul in late 2011, but dialed it back slightly after a backlash accused her of supporting Paul's racist and homophobic publications, <a href="http://www.foxnews.com/entertainment/2012/03/09/kelly-clarkson-never-endorsed-ron-paul/" target="_hplink">reports Fox News</a>. (Photo by ROBYN BECK/AFP/Getty Images)

  • Snoop Dogg & Ron Paul

    In December 2011, Snoop Dogg posted a picture of Ron Paul on his Facebook page with the caption "Smoke Weed Every Day," <a href="http://www.reuters.com/article/2012/01/31/us-snoopdogg-ronpaul-idUSTRE80U04220120131" target="_hplink">reports Reuters</a>. (Photo by Ethan Miller/Getty Images for Keep Memory Alive)

  • Oliver Stone & Ron Paul

    In January, Oliver Stone told <a href="http://www.rockcellarmagazine.com/2012/01/12/director-oliver-stone-on-history-and-america-jim-morrison-ron-paul/" target="_hplink">Rock Cellar Magazine</a> that he would vote for Ron Paul over Barack Obama if Paul was named the GOP nominee because "he's the only one of anybody who's saying anything intelligent about the future of the world." (Photo by Stephen Morton/Getty Images)