President Trump has fired Michael Atkinson, the inspector general for the U.S. intelligence community who alerted Congress to concerns about a Trump phone call with the president of Ukraine – a matter that led to the president’s impeachment last year.

Trump formally notified the intelligence committees of both the Senate and House in a letter dated Friday. House Intelligence Committee Chairman Adam Schiff, D-Calif., posted the letter online.

"This is to advise that I am exercising my power as President to remove from office the Inspector General of the Intelligence Community, effective 30 days from today," the president wrote.

HOUSE INTEL REPUBLICANS INVESTIGATING INSPECTIOR GENERAL HANDLING OF WHISTLEBLOWER COMPLAINT

"It is extremely important that we promote the economy, efficiency, and the effectiveness of Federal programs and activities. The Inspectors General have a critical role in the achievement of these goals," the president continued. "As is the case with regard to other positions where I, as President, have the power of appointment, by and with the advice and consent of the Senate, it is vital that I have the fullest confidence in the appointees serving as Inspectors General. That is no longer the case with regard to this Inspector General."

The president added he would nominate a replacement "who has my full confidence and who meets the appropriate qualifications," at a later time.

Tom Monheim, a career intelligence professional, will be named acting inspector general for the intelligence community, an intelligence official who requested anonymity told The Associated Press. Monheim is currently general counsel of the National Geospatial-Intelligence Agency.

Democrats react

Leading Democrats quickly criticized the president's action.

In a statement, Schiff claimed the move puts the country "at even greater risk."

"Trump’s dead of night decision to fire ICIG Michael Atkinson is another blatant attempt to gut the independence of the Intelligence Community and retaliate against those who dare to expose presidential wrongdoing," he said.

House Speaker Nancy Pelosi, D-Calif., blasted the president's move as "a brazen act against a patriotic public servant who has honorably performed his duty to protect the Constitution and our national security, as required by the law and by his oath.

“This latest act of reprisal against the Intelligence Community threatens to have a chilling effect against all willing to speak truth to power," Pelosi continued. "The President must immediately cease his attacks on those who sacrifice to keep America safe, particularly during this time of national emergency.”

Senate Minority Leader Chuck Schumer, D-N.Y., condemned the president's action in a pair of late-night Twitter messages.

"Whether it's LTC Vindman, Captain Crozier, or Intelligence Community Inspector General Michael Atkinson: President Trump fires people for telling the truth," Schumer wrote in one message.

"Michael Atkinson is a man of integrity who has served our nation for almost two decades," he added in a second post. "Being fired for having the courage to speak truth to power makes him a patriot."

Horowitz responds

Michael Horowitz, chairman of the Council of the Inspectors General on Integrity and Efficiency and the inspector general at the Department of Justice, criticized the removal of Atkinson and defended his handling of the Ukraine case.

“Inspector General Atkinson is known throughout the Inspector General community for his integrity, professionalism, and commitment to the rule of law and independent oversight,” Horowitz told the AP.

House GOP investigation

In January, Fox News reported that Atkinson was being investigated by Republican members of the House Intelligence Committee for his handling of the Ukraine matter, which began with a complaint filed by an unidentified "whistleblower."

Last August, Atkinson received a complaint from someone who raised concerns about Trump's July 25 phone call with Ukrainian President Volodymyr Zelensky, in which Trump sought a Ukraine-led investigation into the past business dealings in the country of former Vice President Joe Biden and his son Hunter Biden.

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Democrats argued that the president had tied the investigation request to the withholding of U.S. military aid from Ukraine, in what they described as a "quid pro quo" arrangement. But Trump denied any wrongdoing in connection with Ukraine.

The House ultimately impeached Trump on charges of abuse of power and obstruction of Congress -- but the Senate acquitted Trump of the charges in February.

Fox News' Brooke Singman and The Associated Press contributed to this story.