In interviews, Mr. Trump’s supporters said they were determined to harness the anti-establishment energy that Mr. Trump had catalyzed and to refocus it on the Republican leadership in Congress — a target many of them seem just as eager to take down as they are to bring down Mrs. Clinton.

“There’s a huge chunk of people who want to see a fight taken to D.C.,” said Representative Dave Brat, Republican of Virginia and a member of the House Freedom Caucus, which has pressed Mr. Ryan on several issues since he became speaker last year. Mr. Brat said many conservatives remained perplexed as to why Mr. Ryan and Republican leaders would choose to fight Mr. Trump rather than focus their energy on Mrs. Clinton.

“Leadership comes and smacks our guy?” Mr. Brat said. “That’s where you’re going to put down a marker? Really? And the American people are just scratching their head saying, ‘Really? That’s rich.’”

Mr. Brat’s advice for Mr. Ryan: “He’d better pivot. He’d better pivot hard.”