While Jeb Bush feuds with Donald Trump and others kowtow to him, only one candidate is seriously gaining on him.

Ben Carson is now tied with Trump in one Iowa poll and is close in others. His rise suggests that it’s possible to catch the populist wave roiling Republican politics and yet not be an obnoxious braggart.

Ben Carson is a superior outsider to Donald Trump. He is more gentlemanly and more conservative, with a more compelling life story. He is a man of faith who, despite his manifest accomplishments, has a quiet dignity and winsome modesty about him. Ben Carson is a throwback, whereas Donald Trump is a boldfaced name straight out of our swinish celebrity culture.

What they have in common is that they are political neophytes who are memorable communicators precisely because they speak and carry themselves so differently from other candidates. Although the similarities stop there — Carson is what Trump calls “low energy,” and yet he makes it work for him.

Few politicians have ever wielded soft-spokenness to such rhetorical effect. Carson aced the Fox debate when in his closing statement he didn’t puff himself up and attempt to soar like candidates always do, but gently said a few nice things about his background as a surgeon, with a touch of humor. It was a hit.

If you like your outsider not to favor higher taxes, not to have once opposed the ban on partial-birth abortion, not to speak favorably of socialized medicine and not to have been an erstwhile booster of Nancy Pelosi and Hillary Clinton, Ben Carson (or Carly Fiorina) is a much better bet than Donald Trump.

And Carson is altogether a more sympathetic figure. He rose from nothing; Trump took over the family real estate business. Carson’s mom was one of 24 kids, had a third-grade education and worked as a domestic; Trump’s father amassed a fortune of $300 million.

Carson is a serious Christian who has a powerful testimonial about getting down on his knees as a young man unable to control his temper and saying, “Lord, unless you help me, I’m not going to make it.”

Trump says he likes “The Art of the Deal” better than any book except the Bible, but he appears to have read just one of them. Trump is the most blatantly secular major presidential candidate since Howard Dean, and will have to do well in the Iowa caucuses that have been won most recently by Rick Santorum, Mike Huckabee and George W. Bush — all men who were earnest about their faith.

Trump is, to say the least, of a different mold. He is a successful creature of our culture of conspicuous display and tasteless braggadocio. It’s no accident that he played himself in WWE wrestling dramas, or that he names everything after himself, or that he doesn’t have enough superlatives for own personal qualities and wealth and accomplishments.

Carson has certainly made the most of his own renown, churning out best-sellers and raking in the speaking fees, but he operates from a baseline of self-respect and respect for others.

It’s impossible to imagine him engaging in juvenile insult wars with random targets of his ire. Or imagine him calling a female journalist a “bimbo” for asking unwelcome questions. Or commenting crudely on women’s appearances.

America long ago turned its back on self-restraint and gentlemanliness. Conservatives were the last holdouts, but their dalliance with Trump makes you wonder if they, too, are willing to surrender to celebrity excess as the new norm.

Ben Carson stands for something different. His personal story shows how true class isn’t about riches, but about character. Donald Trump has all the finest things and, I’d hazard to guess, barely as much class as Ben Carson’s penniless mother struggling to raise her sons had in her pinky.

If conservatives want to flirt with or support an unconventional candidate, Carson provides the opportunity to do it without a guilty conscience.