The president has found success wading into contested governor’s primaries in South Carolina, Georgia and Kansas, and he may have had the most impact with his early support for Representative Ron DeSantis, who is leading in the polls in the Florida governor’s primary.

“If a president wants to reshape the party in his own image, there’s no better way to do that than to impact the outcome of primaries,” said Kris Kobach, the Kansas secretary of state and nominee for governor who got a late endorsement in his primary from Mr. Trump.

The president’s endorsements have largely been done to repay supporters, but Mr. Trump has also sought to solidify new alliances by lending a hand to some former critics. For example, he helped ensure that Senator Dean Heller of Nevada would not have a primary challenger, propelled Representative Martha Roby of Alabama in her runoff, and he even got behind Mitt Romney’s Senate bid in Utah. Each of them, to varying degrees, had criticized the president in 2016.

The White House political director, Bill Stepien, said that Mr. Trump’s endorsement is powerful, “but there are many tools in his political tool kit,” including not engaging openly in a race but working behind the scenes as “party leader.” He said that Nevada was an important example of where the president and his team worked behind the scenes to clear the Senate primary field by nudging a Heller challenger to run for the House instead.

Mr. Lewandowski was even blunter, recalling a Las Vegas dinner he attended in 2017 with Mr. Heller, in which he bluntly told the senator that if he did not fall in line with Mr. Trump, the president’s allies would aggressively target him. “I said, ‘With all due respect, I will not miss,’” Mr. Lewandowski recalled.

This is not to say that Mr. Trump has totally forgiven and forgotten those who denounced his campaign — or that the president’s advisers do not strategically highlight past critiques when they believe it is best for him to stay out of races.