President Donald Trump and fellow Republicans latched onto revelations tying Hillary Clinton's presidential campaign to a dossier of allegations about his ties to Russia, saying Wednesday it was a "disgrace" that Democrats had helped pay for research that produced the document.

"It's just really – it's a very sad commentary on politics in this country," Trump said in addressing reporters one day after news reports revealed that the Clinton campaign and the Democratic National Committee, for several months last year, helped fund research that ultimately ended up in the dossier.

The document, compiled by a former British spy and alleging a compromised relationship between Trump and the Kremlin, has emerged this year as a political flashpoint. Law enforcement officials have worked to corroborate its claims. James Comey, FBI director at the time, advised Trump about the existence of the allegations, and the ex-spy who helped assemble the document, Christopher Steele, has been questioned as part of an ongoing probe into possible co-ordination between Russia and the Trump camp.

Story continues below advertisement

Trump has derided the document as "phoney stuff" and "fake news" and portrayed himself Wednesday as an aggrieved party, posting on Twitter a quote he said was from Fox News that referred to him as "the victim." The new disclosure about the dossier's origins is likely to fuel complaints by Trump and his supporters that the document is merely a collection of salacious and uncorroborated claims.

"Well, I think it's very sad what they've done with this fake dossier," Trump said Wednesday, adding without elaboration that "they paid a tremendous amount of money." He contended that Democrats had initially denied any connection to the document, but now, "they admitted it, and they're embarrassed by it."

Separately Wednesday, the editor of Wikileaks confirmed that his group was approached by Cambridge Analytica, a data firm working for Trump's campaign during the 2016 election.

Julian Assange told The Associated Press that Wikileaks received a "request for information" from Cambridge Analytica. That request, which Assange would not specify, came prior to last November and was rejected. Assange's comments came after The Daily Beast reported that Cambridge Analytica CEO Alexander Nix reached out to Assange during the presidential campaign about the possible release of 33,000 of Hillary Clinton's missing e-mails. Those e-mails have never been publicly released.

A spokesman for Cambridge Analytica did not respond to a request for comment. Robert Mercer, a billionaire Trump supporter, is a backer of Cambridge Analytica. Former White House strategist Steve Bannon served as a vice-president at the company before joining the administration.

Two people familiar with the newly disclosed dossier matter, speaking on condition of anonymity to discuss confidential client matters, told AP the funding arrangement was brokered in the spring of 2016 by a law firm representing the Clinton campaign and the DNC and that it lasted until right before Election Day. The final memo included in the dossier, a version of which was published online by Buzzfeed in January, is dated December 2016, or after the arrangement had ended.

In March of that year, the person said, the law firm of Perkins Coie was approached by Fusion GPS, a political research firm that had already begun research work on Trump on behalf of an unidentified client during the GOP primary. Fusion GPS expressed interest in continuing to create opposition research on Trump, and Perkins Coie engaged it in April 2016 "to perform a variety of research services during the 2016 election cycle," according to a letter from the law firm's general counsel that was obtained by AP.

Story continues below advertisement

The identity of the original client has not been revealed, and one of the people who spoke to AP said the law firm did not know who it was. Trump, however, hinted Wednesday that he might know the identity and that it could eventually become public.

"I have one name in mind," the president said.

It's unclear what Fusion GPS had dug up by the time the law firm hired it, or how much money was involved in the transaction. The Perkins Coie attorney who helped create the arrangement, Marc Elias, did not immediately return an e-mail seeking comment, and representatives of Fusion GPS declined to comment. The Washington Post first reported the funding deal.

The Clinton campaign paid more than $5.6-million to Perkins Coie, recording the expenditures as simply "legal services," according to Federal Election Commission records. The DNC also paid the law firm more than $2.9-million, nearly all of which was reported as "legal and compliance consulting." The DNC did report paying the firm $66,500 for research consulting.

The new disclosure placed fresh attention on the world of opposition research and the techniques that political campaigns employ. Trump Jr.'s eldest son, Donald Trump Jr., received public scrutiny when it was revealed in July that he had met one year earlier with Russians at Trump Tower after being told he would be receiving damaging information on Clinton. In that case, publicly released e-mails show that Trump Jr. had been told the information was part of a Russian government effort to aid his father.

That June 2016 meeting is being investigated by Robert Mueller, the Justice Department's special counsel leading an investigation into whether Trump campaign aides co-ordinated with Russia to influence the outcome of the election.

Story continues below advertisement

In a statement Tuesday night, a DNC spokeswoman said the chairman, Tom Perez, was not part of the decision-making and was unaware that Perkins Coie was working with Fusion GPS.

"But let's be clear, there is a serious federal investigation into the Trump campaign's ties to Russia, and the American public deserves to know what happened," the statement said.

Former Clinton campaign spokesman Brian Fallon said on Twitter that he regretted not knowing about Steele's hiring before the election, and that had he known, "I would have volunteered to go to Europe and try to help him."

"I have no idea what Fusion or Steele were paid, but if even a shred of that dossier ends up helping Mueller, it will prove money well spent," he wrote in another tweet.