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FBI Director James Comey asked Justice Department officials to publicly reject President Donald Trump's claims that former President Barack Obama ordered the wiretapping of Trump Tower, The New York Times reported Sunday. A senior U.S. official confirmed the newspaper's reporting to NBC News.

The Times reported that Comey requested that the Justice Department publicly rebut the president's allegations — which he posted on Twitter without evidence — because the claims are untrue and suggest that the FBI broke the law. Comey's appeal pits him against the president.

But, The Times added, Comey is having difficulty knocking the story down because there are only a few politically appointed Justice Department officials who could approve a statement, as Attorney General Jeff Sessions recused himself from anything pertaining to the government's investigation into alleged connections between Russia and the Trump campaign.

Despite Comey's request, Trump's White House did not back off on Sunday and called for Congress to investigate.

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Related: White House Calls for Probe, Offers No Proof of Wiretapping

"President Donald J. Trump is requesting that as part of their investigation into Russian activity, the congressional intelligence committees exercise their oversight authority to determine whether executive branch investigative powers were abused in 2016," White House Press Secretary Sean Spicer said in a statement. He offered no evidence to back up the allegations, which Trump compared to a scandal of "Nixon/Watergate" proportions.

President Donald Trump leaves the Oval Office to board Marine One at the White House on Friday. Erik S. Lesser / EPA

NBC News has found no evidence that would support his claims, which have been flatly dismissed by the previous administration.

Related: What Does It Take to Get a Legal Wiretap?

An Obama spokesman called Trump's tweets "unequivocally false," and James Clapper, the former director of national intelligence, said on NBC's "Meet the Press" that he had no knowledge of any surveillance of Trump Tower.

Later Sunday, Democrats on the House Judiciary Committee demanded that White House counsel Donald McGahn respond to The Times' report that his office had sought to gain access to what he "believed to be an order issued by the Foreign Intelligence Surveillance Court authorizing some form of surveillance related to Mr. Trump and his associates."

Such an effort would be "inappropriate" and "improper," the lawmakers said in a letter to McGahn obtained by NBC News.

"The independence of the Department of Justice and the FBI is a particular concern when individuals associated with both the Administration and the President's campaign may be the targets of the investigation," the lawmakers said.

Meanwhile, politicians on both sides of the aisle said the White House needed to provide evidence to back up the president's allegations.

"Suffice it to say I don't have any basis — I've never heard that allegation made before by anybody," Sen. Marco Rubio of Florida, a Republican member of the Select Committee on Intelligence, said Sunday.

"I've never seen anything about that anywhere before," Rubio said. "But again, the president put that out there, and now the White House will have to answer as to exactly what he was referring to."