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The top lawmakers on the House Intelligence Committee have asked the Justice Department to turn over by Monday any evidence showing Trump Tower was wiretapped during the 2016 presidential race — an explosive accusation President Trump leveled at former President Obama without providing proof.

The Justice Department Monday afternoon said it called representatives for the intelligence committee's chair and ranking member "to ask for additional time to review the request in compliance with the governing legal authorities and to determine what if any responsive documents may exist."

The request came in a letter sent last week to the acting deputy attorney general by the committee chairman, Devin Nunes (R-Calif.), and its ranking Democrat, Adam Schiff (D-Calif.), congressional aides told NBC News. FBI chief James Comey, who reportedly asked the Justice Department to publicly reject Trump's claim, was also sent a copy of the letter.

Nunes has promised his panel would look into potential surveillance of political parties as part of its broader investigation of Russian meddling in the election.

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Schiff has said he would ask Comey about Trump's accusation when the FBI director appears at a House Intelligence hearing later this month. In an interview on ABC's "This Week" on Sunday, Schiff said he did not expect to see any evidence of wiretapping — but he added that Comey "would be in a position to have to know."

"I think on March 20, if not before, we'll be able to put this to rest," Schiff told ABC's George Stephanopoulos, referring to the date of the upcoming hearing. "I don't think anyone has any question about this, George. The only question is why the president would make up such a thing."

The DOJ today requested additional time to comply, and we are urging that they do so promptly but no later than our hearing on March 20. https://t.co/AyehMR7jYl — Adam Schiff (@RepAdamSchiff) March 13, 2017

Trump, in his infamous March 4 tweets, compared the alleged wiretapping to the Watergate scandal and called Obama a "bad (or sick) guy." Kevin Lewis, a spokesman for Obama, said "any suggestion" that the former president ordered surveillance on Trump was "simply false." Appearing on NBC's "Meet the Press" on March 5, James Clapper, Obama's director of national intelligence, denied that Trump Tower was tapped.

Related: Obama ‘Rolled His Eyes’ at Wiretapping Claims: Source

Democrats have criticized Trump for his unsubstantiated claims, and several congressional Republicans have been leery of them.

In an interview on Sunday, Sen. John McCain (R-Ariz.), the chairman of the Armed Services Committee, implored Trump to show his cards.

"The president has one of two choices — either retract or provide the information that the American people deserve," McCain said in an interview on CNN's "State of the Union." "I have no reason to believe that the charge is true, but I also believe that the president of the United States could clear this up in a minute."

In an interview with CBS' "Face the Nation" broadcast Sunday, House Speaker Paul Ryan said he had not seen anything suggesting Obama wiretapped Trump, joking that Trump's wiretapping tweet storm "wasn't really part of the health care marketing campaign."

Nunes, who served on the executive committee of Trump's transition team, has said he has not yet seen evidence supporting Trump's claim. Speaking to reporters last week, the California congressman dinged the media for taking Trump's words too literally.

"The president is a neophyte to politics," Nunes said on March 7. "He's been doing this a little over a year. I think a lot of the things he says, I think you guys sometimes take literally."