John Bolton, who served as former US President Donald Trump’s national security adviser, told CBS News on Wednesday that he is considering a presidential run, but doesn't have a "precise timeline" on his decision.

“I considered it very seriously in 2016, and ultimately decided not to run. If I did it this year, it would be seriously, not to be a ‘one-issue candidate,’” he said.

Bolton added that he was “very disturbed” when Trump said that the Constitution should be terminated "so that he could be declared the winner of the 2020 presidential election.”

“That’s like calling for the overthrow of the government,” stated Bolton. “I was also disappointed that not enough Republicans explicitly rejected the idea that you can terminate the Constitution and said that kind of thinking is unacceptable in the Republican Party.”

Bolton opined that the Republican Party “has work to do to correct the damage that Trump has done, and at some point, somebody is going to have to be outspoken that he is not a Conservative and not a Republican. He is purely Trumpian.”

Bolton served for 17 months as Trump’s National Security Advisor before he was fired in September of 2019.

Since then, Bolton has published a 592-page book in which he takes frequent shots at Trump, describing him as “erratic” and “foolish” and claiming he behaved “irrationally” and “bizarrely”.

The Justice Department sued to bar the book’s publication, claiming it contains classified information and that Bolton violated a non-disclosure agreement by writing the book. However, a federal US judge later ruled that Bolton can move forward in publishing the book.

Trump, for his part, described Bolton as “one of the dumbest people in government that I’ve had the ‘pleasure’ to work with.”

"A sullen, dull and quiet guy. He added nothing to National Security except, ‘Gee, let’s go to war.’ Also, illegally released much Classified Information. A real dope!" he tweeted in November of 2020.

So far, two candidates have thrown their hat into the ring for the Republican nomination – Trump and former US Ambassador to the UN Nikki Haley, who made her candidacy official on Wednesday. Other candidates are expected to join the race as well.