ABC News' Jonathan Karl, Michael Falcone, Gregory Simmons and Arlette Saenz report:
Mitt Romney and his team in Boston aren't the only ones feverishly vetting potential running mates.
In a non-descript Washington, DC office building within sight of the United States Capitol, a team of more than a dozen Democratic researchers have spent the last few months examining every nook and cranny of the records of several GOP vice presidential contenders.
The researchers work for the super PAC, American Bridge 21st Century, which is unveiling a new website on Friday called VeepMistakes.com. The site features more than 1,300 pages of opposition research and scores of video clips.
Political prognosticators can only speculate who is on Romney's short-list, but now we know who the Democrats are preparing to target. The super PAC is shining their spotlight on three of the mostly likely contenders: former Minnesota Gov. Tim Pawlenty, Ohio Sen. Rob Portman and Florida Sen. Marco Rubio. Their research files, which the group is making public for the first time, also offers a sneak peek at the attacks the Democrats are poised to use against whichever potential V.P. ultimately gets the nod from Romney.
The American Bridge file on Portman, who has been the subject of more speculation than just about anyone else, runs nearly 350 pages. It includes sections on the Ohio senator's legal career, his stints in prior presidential administrations and a rundown of his public statements on a raft of issues - from education to gun control to gay and lesbian rights.
The image of Portman that emerges from the briefing book, which the super PAC, has posted online in full is of a Bush-loving, deficit-increasing, subsidy-hating lobbyist.
One section of the thick file focuses on Portman's work at the firm of Patton Boggs in the 1980s when Portman was a registered lobbyist. The law firm represented Haiti and "according to Portman's registration statement as a foreign agent filed with the Department of Justice, his clients included the Republic of Haiti," the research book notes.
That may sound pretty damning, but while Portman's farm may have worked for Haiti, it appears Portman himself did not. Portman's Senate office provided ABC News with a sworn affidavit from Stuart Pape, the managing director of Patton Boggs. In the affidavit, Pape, a prominent Democratic lobbyist, said of Portman's time with the firm, "at no time did Mr. Portman do any work for any foreign government or any entity of a foreign government."
It also details how the national deficit increased while Portman was director of the Office of Management and Budget under President George W. Bush and how the country's trade deficit with China spiked under his watch as Bush's trade czar.
The Portman file, like the 492-page document for Pawlenty and the 555-page one for Rubio, includes an executive summary of "Top Hits" - the information that American Bridge considers most troublesome for each of the potential running mates. Among Portman's "Top Hits," the group details where the Ohio senator "diverges with Romney on key budget and tax issues."
American Bridge decided to release the information before Romney picks his running mate in order to give fellow Democrats, as well as the press, a head-start on examining the major vulnerabilities of each of the contenders.
"In 2008 nobody was prepared for the disaster that was vice presidential candidate Sarah Palin. And while even Mitt Romney couldn't top that pick, the front runners he's considering are all deeply flawed in their own right," said Rodell Mollineau, president of American Bridge. "This year we are going to make sure that the public has as much information as possible, as early as possible, on the extreme and out of touch positions of the candidates Mitt Romney would put a heartbeat away from the presidency."
In addition to the written material, the super PAC, which was formed primarily as a tracking and research organization, is making public large amounts of video footage of the three vice presidential hopefuls. American Bridge trackers have been following Pawlenty since May 2011, Rubio since this February and Portman since May.
Much of the video is raw and uncut. The Pawlenty collection is particularly vast since it includes clips of the former Minnesota governor campaigning against Romney throughout the primary season.
It features moments like a media availability in Greenfield, N.H. on June 12, 2011 when Pawlenty dubbed the health care plan Romney supported as governor of Massachusetts and the one President Obama pushed, "Obamneycare."
The file also delves into Pawlenty's years as governor of Minnesota, saying that he left the state with a $6.2 billion deficit and that he hired lobbyists to top jobs in his administration.
But that's not all accurate. Minnesota actually had a budget surplus during the fiscal year Pawlenty left office. There was a projected deficit for the following year, but it never materialized, and the next's year's budget was balanced.
When it comes to Rubio, who is favored by many conservatives to be Romney's running mate, American Bridge will attempt to characterize the Florida senator as a politician who not only uses his political office for personal gain, but also one who skirts the line of unethical practices.
American Bridge highlights reports that Rubio obtained no-bid employment contracts for himself at two state agencies - Florida International University and Jackson Memorial Hospital - when they faced budget cutbacks. Rubio was hired to teach political science classes and conduct research part time for $69,000 a year at Florida International University despite the school never posting the job publicly and cutting 200 other jobs that year.
Rubio also secured an $8,000 per month consulting contract at Jackson Memorial Hospital, just months after he helped steer $20 million towards the hospital through the state budget allocation, according to the super PAC's research file.
The document also runs through Rubio's failure to disclose a $135,000 home equity loan from the bank of one of his supporters and the specifics of Rubio's state party credit card scandal. When he served as speaker of the House in Florida, Rubio was accused of charging personal expenses - ranging from purchases at the Apple Store to personal home remodeling to car repair on his family's van damaged at a political event - on the state party's credit card.
As recently as May, Rubio admitted he made a "mistake" in the use of the Republican Party of Florida's credit card but said he personally paid any discrepancies found on his statements.
American Bridge officials emphasized that it may be impossible to know now which nuggets of their research will come back to haunt one of the potential veeps down the road.
"Research is innocuous until it's not," Mollineau told ABC News. "A vote taken several years ago, a speech given to a special interest group, a law signed or vetoed can be harmless until put in the context of a present day campaign."