U.S. President Donald Trump speaks to reporters in the Oval Office of the White House.

Neal Katyal, an acting solicitor general under President Barack Obama, criticized the decision in a statement to NPR , asking, "Who would want to live in a country where its leader could just name the identity of a whistleblower and invite retaliation against him?"

The Democratic Coalition, a super PAC opposing Trump, rebuked the president's action. Christopher C. Alberto, a former federal prosecutor, said in a tweet that "Trump's participation in publicizing the name of the whistleblower is a direct attack on our constitutional republic & national security."

The retweet appears to have since been deleted, and the surfermom77 account where the tweet originated appears to have been removed from Twitter.

President Donald Trump is facing backlash for retweeting over the weekend a post that revealed the name of the supposed whistleblower whose report triggered the Ukraine investigation that eventually led to Trump's impeachment.

Rep. Steve Scalise defended the retweet in an interview with Fox News. "The whistleblower absolutely ought to be known and testify," he said. "This person had a political vendetta against the president," he said. "It's a little concerning that you could have somebody anonymously try to take down a sitting president using innuendo."

The White House did not immediately return a request for comment from CNBC. Under the Whistleblower Protection Act of 1998, whistleblowers are protected from retaliation but neither the president nor members of Congress are prohibited from identifying them.

The retweet was the first time the president has publicly circulated to his 68 million Twitter followers the name of the supposed whistleblower, whose complaint about the president's July 25 phone call with the leader of Ukraine launched the impeachment inquiry in the Democratic-led House of Representatives.

In the call with newly elected Ukrainian President Volodymyr Zelenskiy, Trump pressed his counterpart to investigate the U.S. president's political rival Joe Biden and his son Hunter.

At the time, the White House had held up nearly $400 million in military aid and was dangling an official White House meeting between the two leaders in exchange for a promise to investigate the Bidens.

On a largely party-line vote, the chamber impeached the president on Dec. 18 on two charges: abuse of power and obstruction of Congress.

The proceedings are expected to move to the Republican-controlled Senate for a formal trial of the president, starting in the new year, but Speaker of the House Nancy Pelosi has delayed sending the articles of impeachment to the Senate.

Twitter in an email to CNBC said Trump's retweet is "not a violation of the Twitter Rules." According to Twitter's private information policy, sharing someone's name does not constitute a privacy violation on the social media site.