A GOP-penned memo accusing top officials at the FBI and the Justice Department of political bias was made public on Friday.
President Donald Trump earlier in the day approved the release and accused leaders at the bureau of politicizing the "sacred investigative process."
The president lashed out at federal investigators after he cleared the way for the classified document alleging the FBI abused surveillance powers to track a former Trump campaign adviser to be declassified.
Agency officials say the document is misleading and could jeopardize national security.
"The top Leadership and Investigators of the FBI and the Justice Department have politicized the sacred investigative process in favor of Democrats and against Republicans _ something which would have been unthinkable just a short time ago," Trump wrote.
He added that "Rank & File are great people!"
Some House Republicans have been anxiously awaiting the president's approval to release the memo _ despite warnings from FBI officials who say the document is misleading and could jeopardize national security.
The memo was written by GOP lawmakers to support their claims that investigators abused surveillance tactics in the federal probe into Russian election meddling and possible coordination with Trump associates _ before special counsel Robert Mueller was appointed to take it over.
It asserts anti-Trump bias at the FBI and reveals that deputy attorney general Rod Rosenstein approved an application to extend surveillance of former Trump campaign associate Carter Page.
The memo argues that the initial application for the warrant was based on information from the unverified dossier compiled by former British spy Christopher Steele that contains claims of close ties between Russia and the Trump campaign.
Page, who served as a foreign policy adviser to Trump during the campaign, has been on U.S. counterintelligence radars for years.
Page lived in Moscow for three years starting in 2004 while working with the investment banking firm Merrill Lynch & Co.
In 2013, Page drew the interest of the FBI after meeting with a suspected Russian agent. The Russian, Victor Podobnyy, was charged with posing as a junior attache at the Russian consulate in New York while trying to recruit Page as an intelligence source.
Podobnyy called Page an "idiot" but said he was enthusiastic, according to court documents.
Democrats and Department of Justice officials say the GOP memo "cherry-picks" information from a much longer application to a "secret court" allowed under the Foreign Intelligence Surveillance Act.
Those documents typically run 50 to 60 pages, officials said.
"This is designed to impugn the credibility of the FBI, to undermine the investigation, to give the president additional fodder to attack the investigation. And it's a tremendous disservice to the American people," Rep. Adam Schiff of California, the senior Democrat on the House Intelligence Committee, said on CBS "This Morning."
The FBI agents' union issued a statement backing Director Christopher Wray on Thursday, saying it appreciates him "standing shoulder to shoulder with the men and women of the FBI as we work together to protect our country from criminal and national security threats."
The House Intelligence Committee voted along party lines Monday to put the memo out, giving Trump five days to reject the release under committee rules.
