The White House is standing by President Donald Trump's weekend claim that the Obama administration ordered illegal surveillance on Trump's campaign, urging Congress to investigate the matter despite denials from top intelligence officials.

"You have a number of various and credible news sources showing that there was politically motivated activity all during the campaign and suggesting that there may be more there," senior White House Counselor Kellyanne Conway said Monday on Fox News. "The president's entire point is that the people deserve to know. If we don't know, then let's find out together."

"He's the president of the United States. He has information and intelligence that the rest of us do not, and that's the way it should be for presidents," she added. "Let's investigate this and see where it leads. Let's have the House and Senate intelligence committees do their work and think about whether to include this."

Former Director of National Intelligence James Clapper on Sunday denied that Trump Tower had been wiretapped before the election, telling NBC's "Meet the Press" that "there was no such wiretap activity mounted against the president, the president-elect at the time, or as a candidate, or against his campaign." According to The New York Times, FBI James Comey has asked the Justice Department to publicly refute Trump's claims, made Saturday morning on Twitter, that then-President Barack Obama had ordered wiretapping of Trump Tower before the election.

No such denial has been forthcoming from the Department of Justice, nor from the White House, which on Monday said Trump had rejected Comey's assertion that his allegations were false.

"I think he does," spokeswoman Sarah Huckabee Sanders told ABC News, when asked by George Stephanopoulos if Trump refused to accept Comey's contention. "I think he firmly believes that this is a storyline that has been reported pretty widely by quite a few outlets."

Republicans leading several powerful investigative committees on Monday said they were open to investigating the claims that Obama had ordered intelligence officials to spy on Trump, despite admitting to having seen no evidence to corroborate Trump's assertions.

House Oversight Committee Chairman Jason Chaffetz on Monday told several networks that he would "go into it with eyes wide open."

"Thus far, I have not seen anything directly that would support what the president has said," the Utah Republican told "CBS This Morning."

Nonetheless, he said, "you never know when you turn a corner what you may or may not see."

Chaffetz said that if indeed the court responsible for issuing warrants under the Foreign Intelligence Surveillance Act had granted an order to wiretap Trump Tower, a "paper trail" would exist to prove it.

"The president has at his fingertips tens of billions of dollars in intelligence apparatus," Chaffetz said. "I got to believe, I think, he might have something there, but if not, we're going to find out. I think it's premature to say there's no backing evidence."

House Intelligence Committee Chairman Devin Nunes, R-Calif., said in a statement that his committee would "make inquires into whether the government was conducting surveillance activities on any political party's campaign officials or surrogates."

While Obama, Clapper and Comey have said Trump's allegations that Obama ordered the wiretap were untrue, such denials would not necessarily rule out that another agency had sought and was granted a FISA Court order to surveil Trump.