There's an opening in the Republican race for president. Businessman Donald Trump seems to be losing interest after losing Iowa. Texas Sen. Ted Cruz may be the top choice of conservative Christians who support carpet-bombing, but he still unnerves many mainline conservatives.

Florida Sen. Marco Rubio's plans to ride message discipline and policy pliability into consensus support from the party's corporate elite suffered a setback on Saturday night at the Republican debate in New Hampshire. (The Wall Street Journal editorial board, a pillar of that elite, said that Rubio's "gutting by New Jersey Gov. Chris Christie on Saturday was as complete as any we've seen.") Former surgeon Ben Carson appears ready to take his assiduously compiled list of donors and head off for a lucrative retirement.

"If this were a script," Florida writer Carl Hiaasen wrote last week, "you would now write in a timely entrance by the seasoned, well-credentialed Jeb Bush."

Or you would if you hadn't spent the past year watching the Republican presidential race. Hiaasen wasn't challenging the conventional wisdom, which predicted Bush's doom months ago. A few paragraphs later, Hiaasen affixed the word "desperation" to Bush's candidacy.

Yet, all things considered, Bush may be the most formidable candidate that Republicans could run in the general election.

Christie is fatally flawed for Republicans by virtue of his own record and a scandal that, at the least, involves his top aides' creepy abuse of power. Ohio Gov. John Kasich has a strong record in an important swing state and appears to be the only genuinely happy warrior in the field. But his support for Obamacare's Medicaid expansion in Ohio will almost certainly destroy him in the primary, should he become a serious threat for the nomination. (And, at the end of the day, he's a bit herky-jerky in demeanor for White House duty.)

So that leaves Rubio and Bush among the candidates who don't scare children and moderates. Rubio may or may not be the future. But if Republicans believe their own experts, Bush is probably their best shot in the present.

The Republican National Committee's famously ineffectual "Growth and Opportunity Project," issued in early 2013, urged the party to pass comprehensive immigration reform as a way to reach out to Hispanic and Asian voters who had shunned the party's 2012 nominee. That didn't happen. In this campaign, Trump has dominated the debate, lingering over the fine points of deporting 11 million undocumented immigrants, most of whom are Hispanic and many of whom have American family or friends.

Rubio has probably worn out his welcome with voters who care about this — on both sides of the divide. He ran against "amnesty" in his 2010 race before making immigration reform his baby and then, when the going got tough, abandoned it to the wolves. Conservative immigration restrictionists don't appear willing to forgive or forget; many revile Rubio for switching sides. Apparently, he elicits similar feelings among many immigration supporters. One activist assured me that if Rubio makes it into a general election, he will face blistering criticism, including in Spanish, for his betrayal.

Immigration isn't a decisive issue to most voters, and perhaps Republicans can win in November with a minimal, Romneyesque level of nonwhite votes. It's certainly possible. But it's a hard road the party would do better to avoid. And a Cuban-American nominee won't automatically change the party's defensive posture: a monoracial party appealing to an increasingly multiracial electorate.

Bush, we know, has heavy baggage. His brother's presidency was a disaster, and Americans don't seem eager to resume the family's lease on the White House. Running against former Secretary of State Hillary Clinton, however, whose family tentacles generate a different sort of unease, should take some of the sting out of Bush's predicament.

Not everyone agrees. "Bush would suffer from the Bush family connection," said Emory University political scientist Alan Abramowitz, via e-mail. "The Clinton years were much more positive than the Bush years."

But Bush's family cuts two ways. His Mexican-American wife represents a visceral commitment to immigration, assimilation and a broad definition of the American dream. Bush is obviously comfortable in Hispanic culture. And he would be able to make the case, speaking in fluent Spanish himself if necessary, that he stuck to his pro-immigration stand, risked his campaign by battling Trump and the demagogues — and won. That could be worth a lot.

A December poll of battleground states by Latino Decisions, whose principals also work for Clinton's campaign, showed Bush was the only Republican candidate with a net positive rating among Hispanic voters. (Rubio, by contrast, was a net minus 8.)

Moreover, Bush is knowledgeable enough to think on his feet and experienced, having spent eight years as a popular governor of one of the largest states. Just in case some Republicans out there still think evidence that a candidate can actually succeed at the job is in any way relevant.