The Massachusetts Democratic Party is launching today a first-of-its-kind website that it says contains an unparalleled repository of information about Mitt Romney's record that could be used against the former governor in his White House run.

RomneyFacts.com lays out a wealth of documents: personal financial disclosure statements he filed as governor; policy proposals he put forward in his 2002 campaign; several old campaign ads; and a unique searchable database of campaign contributions from his entire political career.

The party says it will add information to the site in the coming weeks and months.

Party officials and political specialists say they know of no other effort to consolidate such a wide range of detailed information about a single candidate. But they said it is not likely to be the last.

"It's obviously a new application of the Internet, and it strikes me that . . . we'll probably soon have equivalent sites for all the candidates," said F. Christopher Arterton, dean of the Graduate School of Political Management at George Washington University.

While campaigns traditionally gather opposition research and strategically disseminate harmful information about rivals to reporters, the website gives access to raw material for bloggers, journalists, and voters to do their own research.

It also invites people to send their information or insights to the party's telephone and e-mail "hotline" for possible addition to the website.

"For many campaign cycles, 'oppo' research was treated as a covert black art, practiced by people in the shadows and disseminated by whispers from people who started their conversations by saying, 'This is on deep background,' " Lee Rainie, founding director of the Pew Internet & American Life Project, said in an e-mail yesterday after reviewing a prototype of the site provided to the Globe by the state party. "This effort is different because it taps into the new realities of politics in the Internet age."

RomneyFacts.com is clearly a partisan clearinghouse, painting Romney as a "flip-flopper" who has traded in the moderate Republican credentials he presented as a candidate for governor in 2002 for a new set of conservative beliefs in his campaign for president.

Its home page compares statements "Massachusetts Mitt" made on abortion, immigration, stem cell research, and other hot-button issues with those made by "Red State Romney."

Asked about the website, Kevin Madden, a spokesman for the Romney campaign, said: "Democrat party operatives are going to continue to peddle distortions and try and attack the governor in every which way possible. Given their current crop of candidates, the last thing they want to do is to run against Mitt Romney, since he has experience, has demonstrated leadership, and has a stellar record of accomplishment."

John Walsh, chairman of the state Democratic Party and manager of Governor Deval Patrick's 2006 campaign for governor, said the site has two purposes: to show that "Mitt has taken the concept of saying anything to get elected to new levels," and to capitalize on new technology that is reshaping the nation's political landscape.