WASHINGTON - President Donald Trump says it is "a very sad commentary on politics" in the United States that Hillary Clinton, his challenger last year, and the Democratic National Committee funded research that was included in a dossier that made salacious claims about him and his purported links to Russian government operatives.

"I think it is very sad what they’ve done with this fake dossier," Trump said Wednesday as he boarded Air Force One for a political trip to Dallas.

U.S. news media, led by The Washington Post, reported that a Washington lawyer, Marc Elias, who represented Clinton's campaign and the national political organization, hired Fusion GPS, a Washington firm, to conduct the research at a time that Clinton and Trump were locked a tight contest for the presidency that Trump eventually won.

Fusion, in turn, retained Christopher Steele, a former British intelligence officer with ties to the Federal Bureau of Investigation and the U.S. intelligence community. He produced reports alleging a broad conspiracy between the Trump campaign and the Russian government to help him win. The reports also included unsubstantiated claims of Trump encounters with prostitutes and business deals in Russia that were intended as bribes.

"It was made up and I understand they paid a tremendous amount of money. And Hillary Clinton always denied it. The Democrats always denied it, and now only because it is going to come out in a court case, they said 'yes', they did it. They admitted it and they were embarrassed by it, but I think it is a disgrace."

The media accounts said Fusion GPS's political opposition research was originally paid for by an unknown Republican client opposed to Trump before he won the party's presidential nomination, with the undisclosed amount of funding then taken over by the Clinton campaign and the national Democratic party.

Trump has long claimed the ongoing congressional and criminal investigations of his campaign's links to Russia are a "witch hunt" being used by Democratic officials as an explanation for his upset win over Clinton, a former U.S. secretary of state.

The U.S. intelligence community months ago concluded that Russian President Vladimir Putin personally directed an effort to undermine U.S. democratic elections and to help Trump claim the White House. Trump has rejected the notion of any campaign collusion with Russia.

As news of the Democratic payments for the Trump opposition research first surfaced, the president retweeted a summary of the story from his favorite news channel, Fox News: "Clinton campaign & DNC paid for research that led to the anti-Trump Fake News Dossier. The victim here is the President."

Special Counsel Robert Mueller, a former FBI chief, is in the midst of a months-long probe of Trump campaign links to Moscow and whether Trump obstructed justice when he fired another FBI director, James Comey, who was heading the agency's Russia investigation before Mueller took over.

Trump has said he was thinking of "this Russia thing" when he decided to dismiss Comey last May.