Ben Carson and Donald Trump. AP Photo/Mark J. Terrill Retired neurosurgeon Ben Carson, who recently left the race for the Republican presidential nomination, will endorse Donald Trump on Friday morning.

The Washington Post, which first reported the news, notes that the endorsement is the "most high-profile nod" for Trump since former candidate and New Jersey Gov. Chris Christie endorsed the frontrunner.

Carson reportedly met with Trump at Mar-a-Lago, the latter's resort in Florida where the announcement will take place. Carson has "gradually come to see Trump as the GOP's best chance of winning a general election and turning out droves of disengaged voters," according to The Post.

Carson told Fox News earlier in the day that he was leaning toward endorsing Trump, calling him a "thinking individual."

Trump himself confirmed the endorsement during CNN's Republican debate on Thursday night.

"I was with Dr. Ben Carson today, who’s endorsing me, by the way, tomorrow morning," Trump said.

The endorsement comes at somewhat of a surprise, considering the difference in tone between the two. Carson became known for his calm demeanor and refusal to get in the "mud" of politics, as his business manager, Armstrong Williams, once said.

In contrast, Trump is known for his blistering critiques of his rivals, including Carson. Trump once compared Carson's "temper" to that of child molesters.

Trump was "very brutal" in his criticism of Carson, Williams told Business Insider on Thursday. But Carson decided to put it behind him.

"None of it ever bothered Dr. Carson," Williams said. "... It's just politics. This is what they do. But sometimes you just have to rise above all of it and ask what's best for the country."

Carson also thinks Trump has the clearest path to the Republican nomination.

"Dr. Carson feels like the American people have spoken. There's something about Donald Trump being a strong man," Williams said, adding that "neither Rubio nor Cruz have a pathway to the nomination."

"He feels that Donald Trump is probably the best chance of moving America forward, of changing this country," Williams said.

And Carson thinks he might be able to influence Trump, according to Williams.

"He believes deep down that he can have a very profound impact on his thinking, on his temperament and everything else," Williams said. "When he met with Mr. Trump this morning, he saw a different side of him. He saw a humble man who was willing to listen."