WASHINGTON — 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 coordination between Russia and the Trump camp.

Trump has derided the document as “phony 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.”