Mr. Bush said at The Wall Street Journal’s CEO Council in Washington that Republican candidates must be willing to “lose the primary to win the general, without violating your principles.”

“It’s not an easy task, to be honest with you,” he added.

Mr. Bush said he would make a decision about the 2016 race “in short order” and sketched out the sort of campaign that he said Republicans must run to take back the White House. “It has to be much more uplifting, much more positive, much more willing to be practical,” he said.