WASHINGTON — President Donald Trump is threatening to slap tariffs on cars coming to the U.S. from Mexico unless the Mexicans do more to stop the flow of migrants trying to enter the U.S.

Trump had threatened to close down the border this week unless Mexico immediately halted “ALL illegal immigration coming into the United States,” but he backtracked Thursday. He told reporters he would try the “less drastic measure” before resorting to his standing border-closure threat.

He will visit the border Friday during a trip to California.

It was the latest, seemingly sudden attempt at new leverage by a president struggling to solve what his administration has called a border “crisis.”