"A lot of people should be ashamed," says US President Donald Trump after okaying release of the memo denouncing an FBI probe over his campaign's ties with Russia. And Democrats warn of a "constitutional crisis" if Trump fires the head of the probe.

Based on classified materials, the four-page memo claims that the FBI used an unsubstantiated, Democratic-funded research report to obtain a warrant to surveil Trump advisor Carter Page, who had extensive Russian contacts.
Based on classified materials, the four-page memo claims that the FBI used an unsubstantiated, Democratic-funded research report to obtain a warrant to surveil Trump advisor Carter Page, who had extensive Russian contacts. (AFP)

The US Congress released a Republican memo on Friday alleging bias in FBI investigations into his presidential campaign, moments after President Donald Trump authorised the explosive move.

"What's happening in our country is a disgrace," Trump said, announcing that he had declassified the memo drafted by Republican Congressman and former Trump transition team official Devin Nunes. 

"A lot of people should be ashamed," added Trump, who earlier on Friday accused the leaders of the Justice and FBI of politicising their investigation in favour of the Democrats. 

"So I sent it over to Congress. They will do what they're going to do. Whatever they do is fine. It was declassified, and let's see what happens."

The move set up an extraordinary confrontation with the country's top law enforcement authorities, and triggered speculation that FBI Director Christopher Wray would step down just six months into the job.

TRT World's Jon Brain reports from Washington.

"Constitutional crisis"

Trump could trigger a "constitutional crisis" if he uses the contents of a controversial Republican memo as a pretext for firing the head of the Russia probe, top Democrats in Congress warned immediately.

"We write to inform you that we would consider such an unwarranted action as an attempt to obstruct justice in the Russia investigation," Senate Minority Leader Chuck Schumer, House Minority Nancy Pelosi, and eight other key Democrats said in a statement after the release of a declassified memo that alleges abuse of power at the FBI and Department of Justice.

"Firing (Deputy Attorney General) Rod Rosenstein, DOJ Leadership, or (special counsel) Bob Mueller could result in a constitutional crisis of the kind not seen since the Saturday Night Massacre," they said, referring to disgraced president Richard Nixon's orders to fire justice officials during the Watergate scandal.

Memo takes a dig at FBI

Trump's critics allege the memo is designed to undercut special counsel Robert Mueller's investigation of his campaign's ties with Russia, which US intelligence agencies unanimously agree tried to tilt the election in his favour.

Based on classified materials, the four-page document claims that the FBI used an unsubstantiated, Democratic-funded research report to obtain a warrant in 2016 to surveil Trump advisor Carter Page, who had extensive Russian contacts.

The FBI had warned that the memo, crafted by Nunes as chairman of the House Intelligence Committee, contained "material omissions of fact that fundamentally impact the memo's accuracy."

But Trump lashed out hard at the leaders of the FBI and Justice Department as he prepared to declassify the document.

"The top Leadership and Investigators of the FBI and the Justice Department have politicised the sacred investigative process in favour of Democrats and against Republicans," he tweeted.

The president called the alleged bias "something which would have been unthinkable just a short time ago. Rank & File are great people!" 

Counter-memo

The document, which has circulated among many members of Congress, was based on the highly classified, much larger record of the application to obtain a so-called FISA national security warrant in 2016 to surveil Page. 

Democrats have sought approval for the release of their own counter-memo that argues Nunes simplified and "cherry-picks" facts to distort what happened.

A White House spokesman said Trump "would be inclined" to permit the release of such a memo if it passes a security and legal review.

Directly in the firing line were Wray, Attorney General Jeff Sessions and Deputy Attorney General Rod Rosenstein, all chosen last year for their jobs by Trump.

Sessions has stayed out of the fray, but Rosenstein, who directly oversees Mueller's Russia investigation, and Wray have battled Nunes and the White House over the memo since the beginning of the year.

Democrats allege that the ultimate target is Rosenstein, the sole person able to fire Mueller.

Rosenstein and Wray this week lobbied Trump's chief of staff John Kelly, and Paul Ryan, the top Republican in the House of Representatives, against the release.

On Tuesday, the FBI issued an extraordinary public warning that it had "grave concerns about material omissions of fact that fundamentally impact the memo's accuracy."

On Thursday, however, Ryan backed Nunes, characterising the release as an act of transparency and a defence of American civil liberties.

"This memo is not an indictment of the FBI or the Department of Justice," Ryan said.

Republican senators uneasy over fight

Adam Schiff, the top Democrat on the House Intelligence Committee and the author of the still-secret counter-memo, rejected Ryan's explanation, citing the president's own Friday tweet. 

Speaking to CBS on Friday morning, Schiff said the president's tweet made plain that the memo's release was "designed to impugn the credibility of the FBI — to undermine the investigation; to give the president additional fodder to attack the investigation."

"It's a tremendous disservice to the American people, who are going to be misled by this — by the selective use of classified information."

Source: AFP