Washington (AFP) - FBI director James Comey will be in the hot seat Monday facing lawmakers who accuse him of stonewalling Congress, as they demand answers about Donald Trump's potential Russia ties and the president's extraordinary accusation of wiretapping by his predecessor.

BI Director James Comey testifies on Capitol Hill in Washington, Tuesday, Jan. 10, 2017, before the Senate Intelligence Committee hearing on Russian Intelligence Activities. AP Photo/Cliff Owen

Washington (AFP) - FBI director James Comey will be in the hot seat Monday facing lawmakers who accuse him of stonewalling Congress, as they demand answers about Donald Trump's potential Russia ties and the president's extraordinary accusation of wiretapping by his predecessor.

The two explosive issues have preoccupied Republicans and Democrats alike for weeks, robbing Trump's administration of a smoother rollout and raising uncomfortable questions about possible collusion between Trump associates and the Kremlin. The stakes for the tycoon-turned-world-leader could hardly be higher.

Comey will testify before the House Intelligence Committee at an open hearing aimed at investigating Russia's interference in the 2016 election campaign.

National Security Agency director Mike Rogers is also scheduled to testify.

The US intelligence community has publicly blamed Moscow for hacks of the Democratic National Committee last year, and suggested the cyber attacks were aimed at steering the election to a Trump victory.

Russia has denied involvement in the hacks.

Several congressional panels have launched investigations into Russia's alleged interference, including House and Senate intelligence committees, which have jurisdiction over the nation's 17 intelligence agencies, and the House and Senate judiciary committees.

The Federal Bureau of Investigation is also probing Russian interference in the election.

The question remains whether the agency has opened a criminal investigation into possible ties between Trump campaign aides and Russian officials.

Monday's hearing promises to be a very public showdown between the FBI and lawmakers, with the national security world certain to watch whether Comey drops a political bombshell on Washington.

Donald Trump. Drew Angerer/Getty Images

Members of Congress have expressed mounting frustration over the lack of cooperation from the FBI about Russia and Trump's incendiary wiretap claim, which Barack Obama and an array of other officials have flatly denied.

Senate Judiciary Committee chairman Chuck Grassley, a Republican, vented his anger at the Justice Department, which oversees the FBI, by threatening not to hold a vote on Trump's nominee for deputy attorney general until he gets answers from Comey.

The FBI director then trooped up to Capitol Hill on Wednesday to brief Grassley and the judiciary panel's top Democrat, Senator Dianne Feinstein, behind closed doors.

The information discussed was "highly classified," Feinstein told reporters afterward.

"It's really not anything that we can answer any questions about."

Representative Devin Nunes, chairman of the House Intelligence Committee, said Friday that the Justice Department had "fully complied" with the panel's request for any materials related to Trump's wiretapping claim. He would not disclose what was provided.

But Representative Jason Chaffetz, chairman of the House Committee on Oversight and Government Reform, said that he had yet to see any evidence of wiretapping. If the White House has any, he added on CNN, "Please share it with us."

Trump has denounced the tumult over the Russia connections as a "total witch hunt."

The issue mushroomed last month when Trump's national security adviser Michael Flynn resigned after it was revealed he misled top officials over his contacts with Russia.

National Security Adviser Michael Flynn, arrives for the President Donald Trump, Japanese Prime Minister Shinzo Abe joint new conference in the East Room of the White House, in Washington, Friday, Feb. 10, 2017. AP Photo/Carolyn Kaster

Around the same time, The New York Times reported that US intelligence agents had intercepted calls showing that members of Trump's campaign had repeated contacts with top Russian intelligence officials in the year preceding the November 8 election.

Adding to the intrigue, Attorney General Jeff Sessions recused himself from any Russia-related inquiries after it was learned that he had met twice with the Russian ambassador in the months before Trump took office.

Top officials from both parties have discredited Trump's wiretapping allegation. House Speaker Paul Ryan, as well as the chairmen and top Democrats on the House and Senate intelligence committees, have said they have seen no evidence to back the claim.

In a BBC interview published Saturday, National Security Agency deputy Rick Ledgett called the suggestion -- which a White House spokesman conveyed to reporters -- that British intelligence might have helped spy on Trump "just crazy." British officials have vigorously denounced the allegation.

Still, Trump doubled down on his assertion Friday.

Speaking at a joint news conference with German Chancellor Angela Merkel, he answered a question about the wiretap allegation by referring to the National Security Agency's reported tapping of Merkel's phone years ago.

"As far as wiretapping, I guess, by this past administration, at least we have something in common perhaps," Trump said.