Among the most enviable and least recognized qualities of a presidential candidate is something they share with lottery winners and bowling champions: a talent for dumb luck. And for those politicians blessed with this wholly undeserved and unearned gift, the most valuable form of it, the lucky break coveted over all others, is a lousy opponent.

President Donald Trump demonstrated such talent in abundance in 2016 when he faced the widely despised Hillary Clinton. For anyone who had trouble voting for Trump because of various concerns about his character, the alternative of punching a chad for Clinton made things much easier.

Trump looks all set to get lucky again once Democrats decide which of the current forlorn crop of candidates they want as their nominee in 2020.

Trump looks all set to get lucky again once Democrats decide which of the current forlorn crop of candidates they want as their nominee in 2020. One, Andrew Yang, stooped so low during Thursday night’s Democratic debate in Houston that he decided to start buying votes, saying his campaign would shell out $1,000 a month for a year to 10 families.

Trump is but the latest in a history of presidential candidates bestowed by fortune with the perfect foil.

The handsome John F. Kennedy drew Richard M. Nixon, an untelegenic candidate who found himself in the first televised debate in history looking pale and tired from a recent hospital stay, sporting a five o’clock shadow — and refusing makeup. Lyndon B. Johnson faced off against Barry M. Goldwater, whom he was able to easily cast as an extremist.

Ronald Reagan had Walter Mondale, who promised to raise taxes, the political equivalent of a hockey team putting the goalie on offense. George H.W. Bush had Michael Dukakis, a diminutive, robotic individual who offered a dispassionate answer about the death penalty when asked about his wife being raped and murdered and who staged a ludicrous photo op swallowed up by an M1 Abrams tank. Bill Clinton had ... George H.W. Bush, an awkward campaigner who’d broken his promise not to raise taxes. The list goes on.

This is not to say Trump won’t earn the presidency. Or that he did not in 2016, either. He adroitly tapped into a gold mine of discontent with the established order, understanding the anger in the hinterland far better than the professional politicians and pundits who couldn’t see the problems with the establishment because they were part of it. But he also got lucky with his opponent — and he barely won.

As if to ensure his re-election, the Democrats have come up with former Vice President Joe Biden as the alleged front-runner — at least according to current polls — anointing him the most electable of the lot. This, however, is a theory deeply in want of evidence. Biden has already proven himself unelectable twice, during runs for the 1988 and 2008 Democratic presidential nomination that went exactly nowhere.

What’s more, he offsets Trump’s most glaring weakness — questions about whether his cerebral cortex is functioning smoothly.

What’s more, he offsets Trump’s most glaring weakness — questions about whether his cerebral cortex is functioning smoothly. Already during the current campaign, Biden has forgotten what state he was in, referred to New Jersey Sen. Cory Booker as the president, called the actual commander in chief “President Hump,” proclaimed a preference for truth over facts and briefly relocated mass shootings that had occurred in El Paso, Texas, and Dayton, Ohio, to Houston and Michigan.

On Thursday, while sharper than he has been, the vice president was still unable to get through his opening statement without repeatedly glancing down at his notes. He again referred to a debate opponent as president, this time Sanders. Former San Antonio Mayor Julián Castro blew the dog whistle on Biden’s mental state as loudly as possible. “Are you forgetting already what you said just two minutes ago?” he demanded after the former VP denied he had said people would have to buy into his health care plan.

Last month, Biden unreassuringly proclaimed, “I want to be clear, I’m not going nuts.”

Biden also is poorly positioned to capitalize on another Trump weakness — the president’s incessant lying. This is because the former vice president has been veering from the truth himself, including recent claims that he opposed the Iraq War from the beginning, that he didn’t oppose busing and a story about pinning a silver star on a service member in Afghanistan, which had most of the truth stripped out of it. To be fair, the latter could also speak to Biden’s potentially deteriorating memory.

Neither of the two leftist Democrats running not too far behind Biden, Sens. Elizabeth Warren of Massachusetts and Bernie Sanders of Vermont, holds much chance of winning the presidency in a country where, according to the 2018 Election Day exit polls, a significant portion of voters consider themselves moderates.

Warren supports "Medicare for All," repealing the law criminalizing illegal entry, banning fracking, assessing a carbon tax, canceling most student loan debt, making public colleges and universities free, raising taxes — and spending the revenues — and providing universal child care. Also problematic: She claimed to be Native American despite no clear evidence that this was anything other than a family legend.

Sanders agrees with her on most counts, but with the added general election drawback of being an avowed socialist with the charm of a grumpy uncle. Red faced, scowling and howling hoarsely as if he had been yelling all day, Sanders angrily dismissed criticism on Thursday of his $30 trillion health care plan, which he somehow calculated would save Americans $20 trillion. “I wrote the damn bill,” he growled.

California Sen. Kamala Harris at least seems more reasonable and might do better in a general election. But she has so far been unable to sustain momentum, and her equivocating on issues like health care hasn’t helped. South Bend Mayor Pete Buttigieg has appeal as a clear-thinking, steady personality but runs roughly the 300th largest city in the United States and has shown little ability to appeal to black voters, who are so critical to gaining the Democratic nomination.

Meanwhile, Booker and former Rep. Beto O’Rourke, once touted as charismatic incarnations of the Democrats’ future, revealed themselves to be man-children the minute they jumped into the race. They’re nowhere in the polls. Andrew Yang’s candidacy is centered on his promise to give every American $1,000, no doubt planning to task the agriculture department with developing the seeds for the trees the money will grow on. Other assorted candidates are at about 1 percent or less in the polls and deserve to be there.

Granted, Trump’s luck may run out elsewhere. The economy could tank, or some foreign policy disaster could engulf us. But he will always have his future Democratic opponent to fall back on.