Trump slams 'bogus' Russian dossier and says the FBI is 'tainted' He cited comments made on Fox News.

 -- President Donald Trump may have slowed his tweeting over Christmas break, but now that the holiday is over, he's back at it, going after his critics and the integrity of the Russia investigation.

This morning, Trump tweeted claims made by Fox News commentators about the infamous dossier that contained potentially damaging allegations about Trump's campaign and the candidate himself.

It is unclear what role — if any — the dossier may have played in the FBI’s sprawling probe, which began in earnest last year after suspected Russian operatives hacked the Democratic National Committee. The dossier is uncorroborated but not disproved.

"WOW, @foxandfriends "Dossier is bogus. Clinton Campaign, DNC funded Dossier. FBI CANNOT (after all of this time) VERIFY CLAIMS IN DOSSIER OF RUSSIA/TRUMP COLLUSION. FBI TAINTED.” And they used this Crooked Hillary pile of garbage as the basis for going after the Trump Campaign!" he wrote.

The comments that Trump referenced in the tweet were made by both a Fox News reporter who was hosting the morning show, Todd Piro, and former congressman and current Fox News contributor Jason Chaffetz.

During this morning's show, Piro asked "Why would you brief members of the FBI before verifying the existence of collusion and really taint the entire FBI in the process?"

Chaffetz then responded at length, adding at one point that "the dossier, we have long known, is bogus."

Chaffetz also said that the dossier was funded with "nefarious ties," going on to say "perhaps even with the Clinton campaign."

ABC News reported last August that Fusion GPS was paid by a still-unknown Republican during that party's primaries to dig up dirt on Trump. The firm later worked for Democrats, who wanted to do the same, according to political operatives.

Last month, Hillary Clinton defended her campaign retaining the firm to conduct opposition research.

“This was research started by a Republican donor during the Republican primary, and when Trump got the nomination for the Republican Party, the people doing it came to my campaign lawyer,” Clinton said on "The Daily Show with Trevor Noah."

“He said 'yes,'” Clinton added. “He’s an experienced lawyer, he knows what the law is, he knows what opposition research is.”

The 35-page dossier, prepared by a former British spy, Christopher Steele, alleges the Trump campaign colluded with the Russians, and includes uncorroborated, salacious allegations about Trump himself, which he has repeatedly denied.

"It’s all fake news," Trump previously said about the claims in the dossier. "It’s phony stuff. It didn’t happen."

This morning is not the first time Trump has tweeted about the dossier, citing Fox News.

"Clinton campaign & DNC paid for research that led to the anti-Trump Fake News Dossier. The victim here is the President." @FoxNews" Trump wrote in an Oct. 25 tweet.