But the way the Republican hopefuls are running is just as instructive. Even as they try to win over the sort of conservative activists dedicated enough to participate in a rare April election, the Republicans are casting themselves more as can-do pragmatists in the spirit of Mr. Trump than unwavering ideologues. At the forum and in individual interviews afterward, three of the Republicans in the 18-person field invoked some variation of Ronald Reagan’s maxim that it is better to get 80 percent of what you want than nothing at all.

Few embraced the Tea Party moniker. And none of the highest-polling candidates pledged to join the Freedom Caucus, the hard-line conservative group whose uncompromising ideology helped derail Mr. Trump’s efforts to repeal the Affordable Care Act.

One of the leading Republican candidates, Karen Handel, even wore her practicality as a badge of honor, citing not just Reagan but also Margaret Thatcher’s “relentless incrementalism” credo.

“Republican voters are expecting that we get down to business and deliver and do the job,” said Ms. Handel, a former Georgia secretary of state, failed Senate candidate and failed gubernatorial candidate. This time around, she said, the expectations from the party base have shifted.