President Trump has told advisers that he is eager to strip more security clearances as part of an escalating attack against people who have criticized him or played a role in the investigation of alleged Russian interference in the 2016 presidential campaign, two White House officials said. 

Over the past 19 months, Trump has fired or threatened to take action against nearly a dozen current and former officials associated with the inquiry, which he has labeled a “rigged witch hunt,” including former FBI director James B. Comey, former deputy attorney general Sally Yates and former FBI deputy director Andrew McCabe. All three were dismissed.

Trump intensified his attacks this week by stripping former CIA director John Brennan of his security clearance and announcing that others are under review. Brennan and former director of national intelligence James R. Clapper Jr., who is on Trump’s review list, were among the Obama administration officials who briefed Trump before his inauguration on evidence of Russia’s interference in the campaign.

President Trump revoking former CIA director John Brennan’s security clearance sparked questions for White House press secretary Sarah Huckabee Sanders Aug. 15. (Monica Akhtar/The Washington Post)

The president has repeatedly urged Attorney General Jeff Sessions and other officials to end the investigation led by special counsel Robert S. Mueller III, who is examining potential collusion between Moscow and the Trump campaign and whether the president has sought to obstruct justice.

To critics, Trump’s moves echo President Richard Nixon’s decision to force the abrupt firing of Watergate special counsel Archibald Cox. 

“If you did all this in one day, it would have a ‘Saturday night massacre’ odor to it,” said Benjamin Wittes, a Brookings Institution fellow who oversees the Lawfare Blog on national security issues, referring to the 1973 move by Nixon that prompted resignations by the Justice Department’s top two officials. “But you spread it out and get people used to the first one, then you do the second one — over a long period of time, it becomes the new normal.”

White House press secretary Sarah Huckabee Sanders read a statement from President Trump revoking ex-CIA director John Brennan's security clearance on Aug. 15. (Reuters)

Many of Brennan’s former colleagues have rallied to his defense. 

“I would consider it an honor if you would revoke my security clearance as well, so I can add my name to the list of men and women who have spoken up against your presidency,” retired Navy Adm. William H. McRaven, who oversaw the 2011 Navy SEAL raid that killed Osama bin Laden, wrote to Trump in an op-ed for The Washington Post. “If you think for a moment that your McCarthy-era tactics will suppress the voices of criticism, you are sadly mistaken.”

Late Thursday, a group of 11 former CIA directors and a former director of national intelligence issued a joint statement calling Trump’s move against Brennan “an attempt to stifle free speech.”

Inside the West Wing, Trump is eager to move against others on the security clearance review list and could act soon, according to the White House officials, who spoke on the condition of anonymity to discuss internal deliberations.

Trump believes he has emerged looking strong and decisive in his escalating feud with Brennan, the aides said, adding that he shows a visceral disdain for the former CIA director when he sees him on TV.

But other aides would prefer a more thorough process or that he drop the matter altogether, and they are scrambling to review the list of people Trump says he would like to strip of clearances. These officials said Trump did not focus on his power to remove clearances until this summer.

Still, as the Russia probe tightens around Trump — Mueller is pressing his legal team over a potential interview with him — the president remains impulsive and unpredictable, aides said.

“The process is essentially meaningless,” one White House aide said. “If Trump wants to do it, he’ll just do it.”

Trump has frequently overruled, contradicted or ignored his aides, and that internal discord was on display again in the move against Brennan.

White House press secretary Sarah Huckabee Sanders announced the action Wednesday by reading a statement in Trump’s name, citing Brennan’s “erratic conduct” and “wild outbursts” on television and allegedly erroneous statements he had made.

Later that afternoon, Trump summoned a Wall Street Journal reporter into the Oval Office for an impromptu interview in which he linked Brennan’s clearance revocation to the “sham” Russia investigation. “These people led it,” he said, referring to Brennan and others. “So I think it’s something that had to be done.”

In an op-ed published Thursday by the New York Times, Brennan called Trump’s claims that there was no collusion between the Trump campaign and Russia “hogwash.”

Brennan characterized Trump’s action as “politically motivated” and said it was “an attempt to scare into silence others who might dare to challenge him.”

Rudolph W. Giuliani, Trump’s lead attorney for the special counsel investigation, dismissed suggestions that the president had developed an “enemies list,” saying that decisions on security clearances will be made on a “case-by-case basis.”

“The basis for having it is the president is going to call on you for advice — if that doesn’t exist, there’s no reason for you to have a clearance,” Giuliani said in an interview. “We aren’t prohibiting their First Amendment rights. We are just saying, you don’t get to see top-secret government documents.”

White House aides confirmed that Trump made his decision weeks ago about Brennan, who serves as an NBC News contributor. Senior advisers, including Sanders, recommended to the president that they announce the action Wednesday amid an onslaught of news coverage from former Trump aide Omarosa Manigault Newman’s new book, which accuses Trump of having made racist remarks, the aides said.

Brennan attacked Trump for calling Manigault Newman a “dog” hours before the clearance was taken away. Trump has obsessed over the book and media coverage of it for several days, aides said. 

Trump grew increasingly agitated about Brennan and others earlier in the summer, believing they were exploiting their credentials as former national security officials to make money, aides said. The president mentioned the Russia investigation when discussing the matter in private and drafted a list of officials who have angered him for Sanders to read at the lectern in the White House briefing room, the aides said. 

Although advisers cautioned the president that some people on the list — including Comey and McCabe — had already lost their security clearances when they were fired, Trump insisted that they be included anyway, the senior officials said. 

Brennan was too “political,” Trump told his aides. The president did not get much resistance from his inner circle because Brennan is widely disliked in the West Wing, according to a senior official and a former administration official, who spoke on the condition of anonymity to discuss internal deliberations.

Mark Zaid, a national security lawyer in Washington, called Trump’s move unprecedented and said Brennan could pursue a due process claim. But he said it is unlikely that Brennan could win his clearance back. “He may have a whistleblower claim because Trump tied it to Russia,” Zaid said. 

“What we’re concerned about is how much further is it going to go?” he added, referring to other potential Trump targets. 

Also on Trump’s list are former FBI employees Peter Strzok and Lisa Page, who criticized the president in private texts while carrying on an affair during their work on agency probes of the presidential campaigns of Trump and Hillary Clinton. Page resigned in May, and Strzok was fired last week

The only current official known to be in Trump’s review is Bruce Ohr, a Justice Department employee who was demoted recently after Republicans named him in a memo earlier this year that targeted his ties to the former British intelligence officer who wrote a controversial dossier about the Trump campaign’s alleged contacts with Russian officials. 

Trump named Ohr and his wife in two critical tweets this week.

The president’s moves have elicited mixed responses among Republicans on Capitol Hill, most of whom have supported his right to remove Brennan’s clearance. 

Sen. Richard Burr (N.C.), chairman of the Senate Intelligence Committee, criticized Brennan for his remarks about potential collusion between the Trump campaign and Russia. If the claim is “purely political and based on conjecture, the president has full authority to revoke his security clearance as head of the Executive Branch,” Burr said in a statement Thursday.

John Wagner and Karoun Demirjian contributed to this report.