Sen. Bob Corker — who has questioned President Trump’s competence and stability, saying he was treating the presidency “like a reality show” – stood by his criticisms Monday and said his thoughts “were all thought out.”

“Look, I didn’t just blurt them out,” the Tennessee Republican, who will not run for re-election in 2018, told CNN. “My comments — my comments, I stand by them — yes.”

Corker said his frustration with Trump had been “building for some time” after he tried repeatedly to share his concerns privately and in meetings.

“Look, I’ve been expressing concerns for some time and it’s built over time. I’ve had private dinners, I’ve had private phone calls, I’ve tried to intervene on topics that I thought things were going in a different direction and are not going to be good for our country,” he told the news network.

Corker also weighed in on Team Trump’s intensifying efforts to overhaul the tax code, saying he would oppose any tax-cut bill that would raise the deficit.

“I mean, I’ve stated that clearly,” he said. “I’m very concerned as everyone knows and have been for 10 years and nine months since I’ve been here about our deficits. And I want to make sure that it’s not something that increases deficits, and I also want it to be tax reform.”

Corker also said he spoke with Treasury Secretary Steven Mnuchin about tax-reform matters.

“I’ve had (conversations) up-and-down from (Vice President Mike) Pence, to our Treasury Secretary Mnuchin to (Secretary of State Rex) Tillerson to just like we always do,” Corker said of his conversations in the past week.

Despite their testy relationship, Trump also needs Corker, chairman of the Senate Foreign Relations Committee, to help usher through new legislation on the Iran nuclear accord, which the president decertified.

Corker argued that the Trump administration needs to allay European fears that the legislation would not blow up the nuclear accord.

“It is something that can only work if the administration exercises tremendous diplomacy with our European allies,” Corker said.

Corker recently told The New York Times that Trump is treating the White House like a “reality show” and pushing the US “on the path of World War III.”

”I know for a fact that every single day at the White House, it’s a situation of trying to contain him,” Corker told the paper.

Trump earlier tweeted that Corker had “begged” him to endorse him for re-election.

“I said ’NO’ and he dropped out (said he could not win without … my endorsement),” Trump tweeted. “He also wanted to be Secretary of State, I said ’NO THANKS.’ He is also largely responsible for the horrendous Iran Deal!”

“Hence, I would fully expect Corker to be a negative voice and stand in the way of our great agenda. Didn’t have the guts to run!” Trump added.

Corker tweeted in response: “It’s a shame the White House has become an adult day care center. Someone obviously missed their shift this morning.”

When asked about reports that Tillerson had referred to the president as a “moron,” Corker said Tillerson, Defense Secretary James Mattis and White House Chief of Staff John Kelly “are those people that help separate our country from chaos.”

Corker also assailed Trump in August for his comments about a white nationalist rally in Charlottesville, Va., that turned violent, with Trump blaming “both sides” for the mayhem.

“The president has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate in order to be successful,” Corker said.