WASHINGTON (Reuters) - U.S. Senator Susan Collins, a Republican member of the Intelligence Committee, said Democrats should be called again to testify about reports that their party and Hillary Clinton’s presidential campaign paid for parts of a dossier that detailed accusations about President Donald Trump’s ties to Russia.

U.S. Senator Susan Collins speaks at the Penobscot Bay Regional Chamber of Commerce's Quarterly Business Breakfast in Rockport, Maine, U.S., October 13, 2017. REUTERS/Joel Page

The Washington Post reported last week that Marc Elias, a lawyer for 2016 Democratic presidential candidate Clinton, used campaign funds to hire Fusion GPS, the firm behind the dossier. Committees in both chambers of Congress have been investigating the origin and contents of the document.

John Podesta, who was Clinton’s campaign chairman, and U.S. Representative Debbie Wasserman Schultz, who was the head of the Democratic National Committee at the time, as well as Elias “absolutely need to be recalled” to testify,” Collins said in an appearance on CBS’ “Face the Nation.”

“It’s difficult to imagine that a campaign chairman, that the head of the DNC would not know of an expenditure of this magnitude and significance,” Collins said. “But perhaps there’s something more going on here. But certainly, it’s worth additional questioning of those two witnesses. And the lawyer; absolutely, he more than anyone.”

It has been widely reported that supporters of Republican Jeb Bush, a primary opponent of Trump, initially paid for the firm’s research. Perkins Coie, Elias’ law firm, confirmed on Tuesday that it had hired Fusion GPS in April 2016.

The Washington Free Beacon, a conservative online publication backed by billionaire Republican megadonor Paul Singer, said on Friday it was the original funder of the Fusion GPS project to compile opposition research on multiple Republican presidential candidates, including Trump.

Known as the Steele dossier because it was compiled by former MI6 officer Christopher Steele, the document identified Russian businessmen and others who U.S. intelligence analysts have concluded are Russian intelligence officers or working on behalf of the Russian government.

Representative Trey Gowdy, a Republican who runs the House Oversight Committee, said in an appearance on “Fox News Sunday” that he was more interested in whether the Federal Bureau of Investigation or the Department of Justice used the dossier in conducting their own probes.

“I don’t expect the (Democratic National Committee) to be objective,” Gowdy said. “Almost by definition, opposition research is not objective.

“The next thing that House Intel is trying to find out is whether or not the U.S. government relied on it.”