Rep. Devin Nunes (R-Calif.), chairman of the House Intelligence Committee, answers questions during a news conference March 2. (Win McNamee/Getty Images)

The Republican chairman and ranking Democrat on the House Intelligence Committee said Sunday that new documents provided to Congress by the Justice Department provided no proof to support President Trump’s claim that his predecessor had ordered wiretaps of Trump Tower.

“Was there a physical wiretap of Trump Tower? No, but there never was, and the information we got on Friday continues to lead us in that direction,” Rep. Devin Nunes (R-Calif.), the chairman, said on “Fox News Sunday.”

He added, “There was no FISA warrant that I’m aware of to tap Trump Tower” — a reference to the Foreign Intelligence Surveillance Act, a federal law that governs the issuance of search warrants in U.S. intelligence gathering.

Rep. Adam Schiff (Calif.), the panel’s top Democrat, also said there is no proof of a wiretap: “We are at the bottom of this: There is nothing at the bottom.”

Nunes and Schiff spoke a day before their panel is scheduled to have its first public hearing on alleged Russian attempts to interfere in last year’s presidential election — a subject that is certain to include discussion of contacts between Trump campaign figures and Russian operatives. Trump’s first national security adviser, Michael Flynn, resigned last month after it was revealed that he had privately discussed U.S. sanctions with the Russian ambassador to Washington before Trump took office.

A day before FBI Director James B. Comey appears before the House Intelligence Committee, Republican and Democratic lawmakers on March 19 said they yet have to see any evidence to support President Trump's claim that former president Barack Obama ordered a wiretap on him in 2016. (Bastien Inzaurralde/The Washington Post)

Schiff, speaking on NBC’s “Meet the Press,” said he expects FBI Director James B. Comey to testify clearly at the hearing that there is no factual basis for Trump’s wiretapping claims.

“I hope that we can put an end to this wild goose chase, because what the president said was just patently false,” the Democrat said. “It’s continuing to grow in terms of damage, and he needs to put an end to this.”

Comey privately told lawmakers last week that there is no basis whatsoever for Trump’s claim. “It was a categorical denial,” said a U.S. official familiar with the matter.​ The FBI chief is expected to say so publicly on Monday at hearings scheduled to begin at 10 a.m.

Although they agreed on the wiretapping claims, Nunes and Schiff did not agree on whether the question of collusion between Trump campaign figures and Russian operatives has been settled.

Nunes said the new Justice Department documents, submitted Friday in response to a congressional request, included “no evidence of collusion” to swing the election in Trump’s favor and repeated previous statements that there is no credible proof that there was any active coordination. The lawmaker said he remains primarily concerned about leaks of U.S. surveillance of conversations between Flynn and Ambassador Sergey Kislyak.

“That’s the only crime we know has been committed right now,” Nunes said.

But Schiff said there was “circumstantial evidence of collusion” at the outset of the congressional investigations into purported Russian election meddling, as well as “direct evidence” that Trump campaign figures sought to deceive the public about their interactions with Russian figures.

“Of course, there’s one thing to say there’s evidence; there’s another thing to say we can prove this or prove it beyond a reasonable doubt,” he said. “But there was certainly enough for us to conduct an investigation. The American people have a right to know, and in order to defend ourselves, we need to know whether the circumstantial evidence of collusion and direct evidence of deception is indicative of more.”

Trump last week refused to back down from his tweets on March 4 that claimed President Barack Obama “had my ‘wires tapped’ in Trump Tower just before the victory” and compared it to McCarthyism and the Watergate scandal. But no credible evidence has emerged to support those claims, and the top Republican and Democrat on the Senate Intelligence Committee said last week that they have seen nothing that supports the allegation.

In a Fox News Channel interview on Thursday, Trump said, “I think you’re going to find some very interesting items coming to the forefront over the next two weeks.”

Nunes said Trump could be referring to new information about whether intelligence officials “unmasked,” or identified, U.S. citizens who were captured speaking with foreign officials who are under routine surveillance — a process governed by FISA. “That is very possible, and we don’t have the answers to those questions yet,” he said. “We had a deadline of Friday for the NSA, FBI and CIA to get us those names that were unmasked through the FISA system. We didn’t get those names on Friday, and until we get those names, we can’t rule this out.”

He added that Monday’s hearing is “just the beginning” and that he plans to continue looking into who revealed Flynn’s communications with Kislyak.

“We’re trying to get to everyone who, for lack of a better term, was at the crime scene,” he said. “We’re trying to bring them all in, see what they knew, when they knew it, if they knew about the leaks, if they knew about General Flynn’s name being unmasked. These are all questions that we need to get to the bottom of.”

Trump remains under pressure from members of his own party to back off his claims of illegal wiretapping — particularly after the furor intensified last week when White House press secretary Sean Spicer suggested that British intelligence might have played a role in the surveillance. Spicer later apologized for the claim and explained that he had repeated an unverified media report.

Matthew Olsen, a former head of intelligence programs at the Justice Department’s National Security Division and a former general counsel of the National Security Agency, said a claim like Trump’s is “destructive on a couple of levels.”

One, a false claim that the FBI is engaged in illegal activity — acting on a president’s order to wiretap a presidential candidate — “erodes the relationship between the White House and the intelligence community.” But more fundamentally, he said, insisting on such a claim “also erodes public confidence in what comes out of the White House.”​

On ABC’s “This Week,” another Republican on the House Intelligence Committee called on Trump to apologize for accusing Obama of ordering an illegal wiretap.

“To quote my 85-year-old father … it never hurts to say you’re sorry,” said Rep. Will Hurd (Tex.), a former clandestine agent for the CIA. “I think it helps with our allies. We’ve got to make sure that we’re all working together. We live in a very dangerous world, and we can’t do this alone. … It’s not just sorry to the president, but also to the U.K. for the claims or the intimation that the U.K. was involved in this, as well. It doesn’t hurt. And it takes away from the rest of his agenda.”

Hurd said that “some folks will probably be frustrated” by the hearing Monday because the officials set to testify, including Comey, might not be able to elaborate on investigative matters: “There may be an active investigation going on, a criminal investigation. And if there’s an active criminal investigation, we need to allow law enforcement … do their job.”

In a separate interview on “This Week,” Sen. Rand Paul (R-Ky.) focused on the leak of Flynn’s communications with Kislyak and said those within the federal government who might have been responsible should undergo lie-detector tests.

“It is very, very important that whoever released that go to jail, because you cannot have members of the intelligence community listening to the most private and highly classified information and then releasing that to the New York Times,” Paul said. “There can only be a certain handful of people who did that. I would bring them all in. They would have to take lie-detector tests. And, I would say, including the political people, because some political people knew about this as well.”

Paul said, using a term increasingly favored by conservatives for members of the federal bureaucracy, “You will get a ‘deep state.’ You will have an intelligence community that has enormous power if that happens.”

Hurd, however, pushed back on the notion that a deep state was seeking to undermine Trump.

“I spent nine and a half years as an undercover officer. I was the dude in the back alleys at 4 in the morning collecting intelligence to protect our homeland,” he said. “The men and the women in the CIA, they do their job regardless of who is in the White House. Same for NSA. Same for FBI. These men and women are putting themselves in harm’s way.”

If true, the alleged campaign of political interference by Russia, Hurd said, would “go down in the history of Mother Russia as the greatest covert action campaign” it had ever pursued.

“It created a wedge, whether real or perceived, between the White House, the intelligence community and the American public,” he said. “And that’s why, as we go through this review and investigation, it has to be bipartisan. It has to be thorough. And it has to be thoughtful, because we are feeding into this covert-action narrative that the Russians are trying to create.”

Ellen Nakashima contributed to this report.