NEW YORK — The Republican Party faces a long-term challenge in presidential elections because it is defining itself as a gloomy enclave, a collection of pessimists who fear what our country is becoming and where it is going.

The party’s hope deficit helps explain why there’s a boomlet for Jeb Bush, a man who dares to use the word “love” in a paragraph about illegal immigrants.

The flurry doesn’t mean that the former Florida governor is even running for president, let alone that he can win. But Bush is being taken seriously because his approach to politics is so different from what’s on offer from doomsayers who worry that immigrants will undermine the meaning of being American and that the champions of permissiveness will hack away at our moral core.

No wonder Bush’s statement that immigrants entering the country illegally were engaged in “an act of love” was greeted with such disdain by Donald Trump and other Republicans gathered at last weekend’s Freedom Summit in New Hampshire.

Let’s stipulate that people oppose immigration reform for a variety of reasons. Some see any form of amnesty as a reward for breaking the law. Others believe the country would be better off if the flow of future immigrants tilted more toward the affluent and skilled. Still others worry that immigration pushes wages down.

But it’s not just the immigration issue as such that separates Bush from so many in his party. It’s the broader sense of optimism he conveys when he describes an increasingly diverse nation as an asset. He even, on occasion, speaks of active government as a constructive force in American life. And while he is critical of President Obama — he’s a conservative Republican, after all — he does not suggest, as so many in his party do, that because of the 44th president, the United States is on a path to decline and ruin.

Bush is occupying this space because New Jersey governor Chris Christie has lost it for now. His administration’s role in causing traffic Armageddon on the George Washington Bridge last fall and the rapidly multiplying investigations this episode has called forth created Bush’s opportunity.

At least before his immigration comments, Bush seemed to have more appeal than Christie to the party’s right. A Washington Post/ABC News poll last month asked Americans if they would “definitely” vote for, “consider” voting for, or reject various candidates. Among Republicans and independents leaning Republican, Bush drew acceptance across the board from moderate, somewhat conservative and very conservative Republicans. Christie appealed more to moderates. But Christie may be better positioned for a general election contest than Bush in one respect: Christie demonstrates higher levels of minimum consideration among Hispanics and African-Americans.

Three Republicans — who, by the way, also manage to convey some optimism — ran close to Bush in acceptability: Senator Rand Paul of Kentucky, former Arkansas governor Mike Huckabee and Senator Marco Rubio of Florida. But all three were much stronger with the “very conservative” group than with the others. Senator Ted Cruz of Texas, Governor Rick Perry of Texas and Governor Scott Walker of Wisconsin trailed because they were weaker in the moderate and somewhat conservative camps. (Thanks to Peyton Craighill, The Washington Post’s polling manager, for running these numbers.)

These findings point to Bush’s potential not only with a donor class that clearly likes him but also with rank-and-file Republicans. Still, there are many reasons why he may never be the GOP nominee. He’s not the ideal pick for a party that might more profitably choose a younger, forward-looking candidate who could challenge a Hillary Clinton campaign that would inevitably be cast as a combination of restoration and continuity. A Clinton-Bush choice would necessarily prompt comparisons between the Bill Clinton years and the George W. Bush years. Outside Republican ranks, the Clinton era would win rather handily.

But if Jeb Bush doesn’t make it to the mountaintop, he could usefully offer his party lessons on how to avoid being seen as a convocation of cranky old (and not so old) politicians whose most devout wish is to repeal a couple of decades of social change.

For there is a rule in American politics: Hope and optimism nearly always defeat fear and pessimism. Franklin Roosevelt understood this. Ronald Reagan stole optimism from the Democrats, Bill Clinton stole it back, and we all remember who had a 2008 poster carrying the single word, “Hope.”

Republicans need to realize that “the only thing we have to fear is fear itself” works better than “the only thing we have to offer is fear.”

E.J. Dionne’s email address is ejdionne@washpost.com. Twitter: @EJDionne.

Photo: Gage Skidmore via Flickr