When two flawed presidential candidates, President Biden and former President Trump, met in their high-stakes debate Thursday night, each hoped to pass a test in voters’ eyes. Both failed — but Biden’s stumbles, fairly or not, are likely to cost him more than Trump’s.

Biden needed to quell concerns that he’s too old to serve effectively for another four years. His stumbling, occasionally incoherent performance fell far short. He looked every one of his 81 years — markedly less vigorous and crisp than the commanding figure who delivered an effective State of the Union address about four months ago.

Trump, who is 78, needed to look and sound presidential to appeal to voters who doubt his temperament and his stability. He needed to avoid his self-indulgent temptation to claim that every election he loses was rigged and every legal setback he suffers was politically motivated. He failed, too.

The 90-minute debate was a dispiriting race to the bottom, pitting a tongue-tied octogenarian against a pathological liar. Undecided voters looking for a positive reason to vote for one or the other were unlikely to find enlightenment.

But that doesn’t mean it was a tie. If it had been a boxing match — an apt analogy, given its flurries of verbal punches — a referee would probably have awarded Trump a win on points, for two reasons.

First, Biden came into the debate as the candidate who needed to shake up the campaign. Trump has led recent national polls by a hair, but he is clearly ahead in most of the half-dozen battleground states that will decide the election. Biden hoped to change that, so he needed a win.

Second, while Trump missed an opportunity to appeal to undecided voters and expand his support, he did a more effective job than Biden of presenting his favorite talking points. Many of them were untrue and some were nonsensical, but most went unrebutted by either Biden or CNN’s moderators, who had sworn off fact checking for the evening. That left Trump no worse off than when he started.

A debate’s impact often comes down to a few memorable moments. Many voters didn’t watch at all, and some who tuned in didn’t stay for all 90 minutes. But over the next week or two, some of their worst moments will be played and replayed, magnifying their effect.

A few examples of each candidate’s worst moments may convey the flavor of the evening. (A list of their best moments would be sparse.)

Biden’s voice was hoarse and halting, especially early in the debate. He appeared to lose his train of thought more than once; his voice trailed off at the end of several answers. He ended one tangled explanation of his tax proposals with the puzzling phrase: “if we finally beat Medicare.” After another such moment, Trump seized the opportunity to make sure viewers noticed, saying: “I really don’t know what he said at the end of that sentence. I don’t think he knows what he said, either.”

Trump lied with his customary enthusiasm, reeling off bogus claims he has honed in dozens of stump speeches. He said he produced “the greatest economy in the history of our country” during his term as president, but that isn’t true under any definition of economic success. He claimed Democratic states are routinely killing infants “after birth,” a luridly inaccurate description of late-term abortion. He claimed Biden’s immigration policies have allowed “18, 19, could be 20 million” undocumented migrants into the country, a wild exaggeration, and that the Biden administration is “putting them on Social Security and Medicare.” (It isn’t.)

All those whoppers are familiar to anyone who has sat through any of Trump’s rallies; all have been debunked. But there were too many for Biden to knock down one at a time, so he responded: “Everything he just said was a lie.”

And Trump ducked any question he didn’t want to answer — including whether he will abide by the result of the election. “If it’s a fair and legal and good election, absolutely,” he said — but instantly undercut that semi-pledge by claiming that the 2020 election was riddled with fraud. (It wasn’t.)

There are vast differences between these two candidates on important issues before the country, and voters deserved a debate that illuminated their choice. This was not that debate.

Instead, it was a missed opportunity for both candidates — and one that not only damaged Biden’s chances of shaking Trump’s lead, but was certain to reopen the barely suppressed debate among Democrats over whether they have their best possible nominee.

With four months remaining before election day, the race undoubtedly has more twists and turns to come. But Thursday’s debate was surely a pivotal moment — a setback for Biden that he must now try to repair.

Read more from columnist Doyle McManus on Trump and California.