Asked at a Republican Party fundraiser in Broward County, one of the biggest counties in Florida, whether he would be amenable to the No. 2 slot, Mr. Carson said, “I’ve told Mr. Trump that if it was really going to make a big difference I’d be willing to.”

Mr. Carson also told the crowd heavy with supporters of the home-state Sen. Marco Rubio that he didn’t think Mr. Rubio, Ohio Gov. John Kasich or Texas Sen. Ted Cruz could win.

“I looked at the others and I didn’t see path to victory for Rubio or Kasich, and I felt that Cruz was too polarizing and wouldn’t be able to bring across Democrats and independents,” he said Saturday. “We’re in really different type of environment right now where if you can’t extend your base, you’re not going to win, and I’m afraid of what will happen if we lose. ‘’