Donald Trump keeps his claim that President Obama Administration wiretapped the phones in the Trump Tower during the 2016 election campaign, but his top aides in the G.O.P haven't found evidence to support his unsubstantiated assertions.

On Tueday,  top Republicans on Capitol Hill refused to offer personal assurances to back up the President's unsubstantiated claim that Obama wiretapped the Trump Tower phones. 

“We have an existing intelligence committee looking at all aspects of what may have been done last year related to the Russians or the campaign and we’ll leave it there,” Mitch McConnell, the Senate majority leader, said, as reported in The Guardian.

Devin Nunes, the chairman of the House intelligence committee, also could not offer any proof of Trump’s allegations while speaking at a separate press conference.

“At this point, we don’t have any evidence of that,” said Nunes, whose panel is investigating Russian interference in the US election.

At the West Wing, Trump's top aides also refused to give personal assurances about Trump's assertions:

“No, that’s above my pay grade,” said Sean Spicer, the White House press secretary on Tuesday at an on-camera briefing when asked if he had seen any evidence to back up Mr. Trump’s accusation. Mr. Spicer repeatedly refused to offer personal assurances that the president’s statements were true, reported The New York Times.

Early in the day, Attorney General Jeff Sessions also refused to comment. Sessions has recused himself from any investigations involving the Trump campaign’s contacts with Russia.

“I don’t know anything about it,” John F. Kelly, the homeland security secretary, said on CNN on Monday. 

Both the F.B.I. director, James B. Comey, and the former national intelligence director, James R. Clapper Jr., have denied that any such wiretap was requested or issued.

The accusation made by Trump against Obama constitutes one of the most consequential accusations made by one president against another in American history, as reported in The New York Times.

The reaction from Republicans in Washington was the latest example of a familiar pattern: forced to defend the unfiltered words of a president who has a history of making false proclamations with significant consequences. In the six weeks since Trump took office, Republicans have struggled to make sense of claims that have ranged from his false insistence that millions of illegal votes were cast in the November election to now an unprecedented accusation against his predecessor.  As reported in The Guardian.