Doyle McManus, Los Angeles Times

A funny thing happened on the way to Jeb Bush’s long-expected disappearance from the Republican presidential contest: He became a better — and more interesting — candidate.

Improbably, he has Donald Trump to thank for it.

For much of 2015, after launching his campaign as a presumptive frontrunner, Bush watched in miffed disbelief as GOP voters cheered Trump’s uncouth braggadocio.

“I’ve got a lot of really cool things I could do other than sit around being miserable, listening to people demonize me,” Bush said last fall. “That is a joke. Elect Trump if you want that.”

But as Trump’s insults continued, Bush’s standoffish pique morphed into slow-boiling anger.

In recent weeks, the former Florida governor has redefined himself as the anti-Trump, out to save his party from the specter of a nominee without qualifications or polish. The newfound mission has given Bush a clear message, an ingredient his campaign had been missing.

Along the way, he’s shed his politesse to match Trump insult for insult.

“Donald Trump, you aren’t just a loser, you are a liar and a whiner,” Bush taunted, un-Bush-like, on Twitter this week.

In campaign stops across New Hampshire, Bush argued that Trump’s candidacy is a danger not only to the party but also to the country.

“At some point in the next presidency, there will be a crisis,” he said. “Who do you want sitting behind the big desk?”

“Donald Trump organizes his campaign around disparaging people,” he added. “It’s not ‘strong’ to insult women. It’s not ‘strong’ to castigate Hispanics. It’s not ‘strong’ to ridicule the disabled. And it’s certainly not ‘strong’ to call people like John McCain losers.”

The new message apparently gave Bush only a modest boost in New Hampshire, where he finished in the middle of the pack and far behind Trump. But mere tactical advantage isn’t the reason he’s attacking the businessman, Bush told Politico.

“I was offended” by Trump’s campaign, he said. “I still am. ... You don’t insult your way to the White House.”

Before anyone had cast a ballot in New Hampshire, Bush and his aides insisted that he would stay in the race for months to come.

“This is a long-haul process,” he said. “Public sentiment, how people feel, will change. It always does. And if you stick to who you are, the simple fact is you can win the day.”

Bush has other reasons to continue, no matter the odds.

His campaign has more than enough money. At the end of 2015, his super PAC reported $58 million in its coffers.

He has a serious campaign organization in South Carolina, site of the next primary.

One other factor: Bush’s brother, former President George W. Bush, has urged him to stay in. “His advice is consistently: Stay the course, be patient, it’s coming your way,” Bush told Politico. (With a Bush in the race, there’s always a dash of family drama.)

So Bush has found a mission and freed himself from caution.

He’s even migrated back to some of his original, moderate-conservative positions — at least in New Hampshire, where GOP voters are less hard-line than in other places.

At a town meeting in Bedford, he sounded almost like a Democrat on the subject of climate change.

“Look, the climate is changing,” he said. “We have billions of people that live on the planet. We clearly have an impact. To deny it doesn’t make sense.” (He added, though, that huge subsidies for clean-energy projects don’t make sense, either.)

He said he wants to overturn the Supreme Court decision that allowed super PACs (including his own) to raise money anonymously. He still favors unlimited fundraising, he said, but he favors “total transparency” — a position that puts him at odds with GOP leaders in Congress.

And he said one of his central goals as president would be to restore the lost art of bipartisan compromise to Washington.

“I don’t think liberals are bad people,” he said.

Bush is still out of sync with Tea Party voters, who prize ideological purity over deal-making. He’s not likely to win many of Ted Cruz’s voters, but those aren’t the voters he’s aiming for. He’s trying to peel support away from Marco Rubio and Trump.

But when Bush talks about Rubio, his former political protege in Florida, he sounds more disappointed than angry. It’s Trump who elicits his hitherto unglimpsed passion.

“Donald Trump: You’re the loser!” Bush declared in Nashua, New Hampshire.

He’s not merely a candidate; he’s an anti-candidate. Bush may not win, but if he succeeds in denying the nomination to Trump, he’ll count that as one mission accomplished. Trump may yet rue the day he derided Bush as a low-energy loser.

Commenting is limited to Omaha World-Herald subscribers. To sign up, click here.

If you're already a subscriber and need to activate your access or log in, click here.