WASHINGTON —  Mike Waltz is on his way out as President Trump’s national security adviser, three sources familiar with the matter told The Post Thursday.

The former Florida congressman, 51, was at the White House Thursday morning and gave no outward indication that his job was in jeopardy — after more than month in political limbo after he added anti-Trump journalist Jeffrey Goldberg to a Signal group chat about Yemen airstrikes.

Waltz also has taken heat internally for allegedly not giving more respect to chief of staff Susie Wiles, and his position became even more precarious after pro-Trump activist Laura Loomer discovered a 2016 ad in which Waltz bashed Trump.

“He essentially called anyone captured in combat a loser,” Waltz said of the president in that 9-year-old clip. “It’s something that I just personally can’t stomach. Don’t let Trump fool you. Look into his real record and stop Trump now!”

Waltz was one of the few senior Trump aides who previously worked for the George W. Bush administration, including as a counterterrorism adviser to then-Vice President Dick Cheney, whom Trump has ripped as a warmonger.

It was not immediately clear when Waltz’s last day in the administration would be or whether he was terminated with immediate effect. His dismissal was first reported by 2Way co-founder Mark Halperin.

Trump made no public comment about Waltz during his first White House event marking the National Day of Prayer — but the president did make a point of singling out multiple other cabinet officials for praise, including under-fire Defense Secretary Pete Hegseth.

Waltz became embroiled in controversy last month after he admitted to mistakenly adding Goldberg, the editor in chief of The Atlantic, to a Signal group chat of administration officials, during which sensitive information about March 15 strikes targeting Yemen’s Houthis was shared.

At the time, Trump expressed confidence in his national security adviser, telling NBC News March 25 “Michael Waltz has learned a lesson, and he’s a good man.”

However, one source familiar with Waltz’s ouster said that the national security adviser was living on borrowed time, since Trump didn’t want to fire any key staffers in his first 100 days.

“Waltz was a goner the moment Signalgate happened,” this person said, “[Trump] just didn’t wanna fire anyone that early.”

Trump marked his 100th day as the 47th president on Tuesday.

Among the names floated as Waltz’s replacement include Steve Witkoff, Trump’s longtime friend and special envoy to the Middle East as well as the de facto presidential ambassador to Russian President Vladimir Putin.

Michael Anton, the current White House director of policy planning, is also being pushed by key members of Trumpworld — including Vice President JD Vance — two sources said Thursday.

Anton gained notoriety in political circles ahead of the 2016 presidential election when he penned a pseudonymous essay titled “The Flight 93 Election” — likening voting for Hillary Clinton to passengers on the ill-fated 9/11 flight allowing Al Qaeda hijackers to crash the plane rather than charging the cockpit.

State Department spokesperson Tammy Bruce didn’t deny that Waltz would be shown the door Thursday, telling Fox News during a live hit, “I’m not gonna get ahead of what the president may or may not say later today.”

“What I do know is that the talent bench in this country and for this government is deep … the president is engaged in every aspect of the country, and the choices he makes moving forward will be, as usual, excellent and will be in the best interests of the American people.”

White House press secretary Karoline Leavitt, meanwhile, told reporters that “we are not going to respond to reporting from anonymous sources” in response to Halperin’s initial report.