When Donald J. Trump was in the thick of his first campaign for the White House, Jack Ciattarelli, then a Republican state assemblyman mulling a run for governor of New Jersey, called the soon-to-be commander in chief a “charlatan” who was “out of step with American values.”

“Sitting silently and allowing him to embarrass our country is unacceptable,” Mr. Ciattarelli said in a 2015 statement. “He is not fit to be president of the United States.”

Ten years later, Mr. Ciattarelli, the front-runner in the June 10 Republican primary for governor, has pivoted. He has praised Mr. Trump during the campaign and last month earned the president’s coveted endorsement.

Like many other Republican politicians across the country, including the vice president, JD Vance, Mr. Ciattarelli has worked to paper over his past criticism of the president as Mr. Trump has grown in popularity.

That effort to appeal to the G.O.P.’s conservative base is seen more as a reflection of the realities of party primaries at a polarized moment in history than as a fundamental realignment of the Republican Party in New Jersey, a left-leaning state with a high percentage of affluent suburban voters.

“It’s indicative of where Republicans are, but it’s also indicative of where a lot of voters are,” said Peter J. McDonough Jr., a retired political strategist and former aide to Christine Todd Whitman, a Republican who was governor of New Jersey in the 1990s. “People are mad. People are dissatisfied — whether they’re Bernie Sanders or Trump voters.”