Former Secretary of State Hillary Clinton promotes her new book "What Happened" on Monday, Oct. 23, 2017 in Montreal. (Ryan Remiorz/The Canadian Press via AP)

Hillary Clinton and top officials of her presidential campaign were largely silent Wednesday in response to the revelation that the campaign and the Democratic National Committee had paid for research that resulted in a dossier alleging Russian interference on behalf of Donald Trump in the 2016 election.

Neither Clinton nor her campaign manager, Robby Mook, responded to requests for comment Wednesday. Campaign chair John Podesta declined to comment beyond referring reporters to a statement issued the previous day by the campaign's law firm saying officials had not been aware of the arrangement.

Brian Fallon, the former campaign spokesman, said he didn't know about the research at the time but called it "money well spent" if it provided information useful to the special counsel now investigating Russia's involvement.

Trump, meanwhile, told reporters Wednesday that the involvement of the DNC and the Clinton campaign was "a very sad commentary on politics in this country. ... I think it is a disgrace."

The Washington Post reported Tuesday that Democratic attorney Marc E. Elias had retained the research firm Fusion GPS, which later hired Christopher Steele, a former British intelligence agent who had worked on Russia-related issues. Steele drafted reports in 2016 that were later compiled into a dossier alleging Trump had ties to Russia and was benefiting from Kremlin interest in his campaign.

Elias's firm Perkins Coie represented the Clinton campaign and the DNC.

The new report is likely to provide ammunition to Trump and his allies, who have long portrayed the dossier as a partisan document designed to undermine the election results.

U.S. intelligence agencies concluded last year that Russia had intervened in the 2016 election to help elect Trump. But GOP congressional investigators have shown interest in exposing the role that Democratic money played in the dossier, and have questioned whether the FBI's initial inquiries into possible Trump campaign coordination with Russia were driven by partisan concerns.

Officials have said the FBI has confirmed some of the information in the dossier, though not its most sensational accusations. Steele began providing the FBI with information about his research before the election. In September, FBI agents working with special counsel Robert S. Mueller III traveled to London to debrief Steele more thoroughly about his work.

The top Democrat on the House Intelligence Committee, Rep. Adam B. Schiff (Calif.), said he thought Republicans were trying to divert attention from what was important about the dossier, which was already known to have been funded by partisan interests.

"Christopher Steele, no matter who was paying for his services, may have discovered before our own intelligence agencies that the Russians were going to interfere in our election on behalf of Donald Trump," Schiff told MSNBC Tuesday night.

DNC officials were muted in their response to the report that party funds had been used to underwrite Steele's research.

A spokesman for Rep. Debbie Wasserman Schultz (Fla.), who was DNC chairwoman at the time Perkins Coie contracted with Fusion, said Wednesday the former chair was "not aware" of the law firm's arrangement with Fusion.

Federal Election Commission records show that the Clinton campaign paid the Perkins Coie law firm $5.6 million in legal fees from June 2015 to December 2016, according to campaign finance records, and the DNC paid the firm $3.6 million in "legal and compliance consulting'' since November 2015. Some of those total fees were apparently paid to Fusion GPS.

Former top aides to Clinton and the DNC were reluctant to discuss the arrangement Wednesday, but several spoke on the condition of anonymity to defend it.

"This is what campaigns do," one former campaign official said. "It makes sense for a law firm to contract that work and maintain confidentiality because it is extremely risky," the official said.

Adam Entous, Devlin Barrett and Matt Zapotosky contributed to this report.