Could Joe Biden lose it at Thursday’s debate in Houston in a way that confirms he’s too old, too old-fashioned, too tired, too “get off my lawn” for a party that’s skewing young and moving left?

Spoiler: Yes, and that’s the anticipated plot of Thursday’s debate. It will ostensibly be about health care, climate change, guns, gender issues, and education. But in reality all eyes will be on Biden to see if he can take a punch, or a dozen of them. It’s not just Sen. Elizabeth Warren who’s aiming for him, podium to podium for the first time with the leading candidate. All nine of the other Democrats on stage are poised for that moment when Biden’s hair catches on fire. Each is “a” Biden vying to replace “the” Biden.

So far Biden’s faltered, but not enough to knock him out of first place. He wasn’t ready for the left jab from Sen. Kamala Harris about how she was “that girl” who was in a later class of children to be sent to a desegregated school because of his opposition to busing. It was more complicated than that, but the trusted vice president of the first black president seemed to think he was at a church picnic, and couldn’t have been more stunned by the frontal attack. In his performances, he’s been low energy. Who runs out of things to say and yields back their time?

Warren’s coming Thursday armed with chapter and verse on Biden’s record as the Senator from Delaware favoring corporations, the bad guys at the center of most of the detailed reforms that have powered her rise. Will he have her record of taking money from some of those same corporations before she found religion and banned them, or know enough about her policy proposals to make the case they’re impractical? Warren arrives with the wind at her back, drawing by far the biggest crowds, the clear favorite at the mini-convention in New Hampshire this past weekend, getting a two-minute ovation before she said a word.

But Biden has a lot of goodwill stockpiled and he just has to rely less on his instincts and more on briefing books. Even those who admire him are worried about how easily he gets lost in the mists of time and mixes fiction with non-fiction. Every detail in a heart-wrenching story about a war hero he recently told was wrong, as the Washington Post reported: the vice president wasn’t in Afghanistan but the White House, the hero was in the Army, not the Navy; Obama, not Biden, bestowed the Medal of Honor, not the Silver Star. But folks who heard it were still wiping their tears by the time the facts, which Biden doesn’t think matter, caught up with him.

Still, the whispers are getting louder. “I just think Biden is declining,” Rep. Tim Ryan, still running his own campaign after failing to make the debate stage, told Bloomberg News. “I don’t think he has the energy. You see it almost daily. And I love the guy.”

“There’s a clear worry among Biden supporters that he can’t be the front-runner from June of 2019 through July of 2020,” said former Pennsylvania governor and DNC chair Ed Rendell, who is a major supporter and loves the former veep to death. “That eventually, the gaffes will pile up and he’ll come down.”

I’m in the love Biden camp but I’ll be watching him as I do a child at a piano recital: my fists clenched, braced for the first wrong note. Changing the debate from two hours to three is not to Biden’s advantage. He is in excellent shape but at 76, just standing in one place that long under the klieg lights can be a strain and could trigger his tendency to resort to fuddy-duddy verbal tics like “I’m not joking,” “Joey, my mother said to me,” and rambling, like Ronald Reagan, who was the last candidate thought to be too old, taking unplanned detours down the Pacific Coast Highway mid-debate. He won anyway after declaring he wouldn’t hold Walter Mondale’s youth and inexperience against him.

Biden, so far, hasn’t had a quip like that ready, which comes partly from being out of the arena. He got soft from the trickle-down approval as Obama’s number two. After, he took time away to mourn his son’s death, to work on finding a cure for cancer, and deliver paid speeches. Audiences came to hear him, stayed for the hugs, and didn’t call foot faults.

It’s different now and thus the concerns over his “gaffes”—misnamed since a gaffe, as journalist Michael Kinsley noted, is when a politician accidentally blurts out the truth. Biden can handle the truth when he can remember it. He should get straight what state he’s in, and while he was ultimately right on what to do about Iraq, admit that he got the vote wrong. Same about the crime bill. It gave us an assault weapon ban that saved countless lives but it also had unintended consequences. Lapsing into stories about his dad lending him a car off the used car lot for the prom to remind people of his working class cred growing up in Scranton—a little goes a long way.

By this, his third debate, Biden should be in fighting shape. It may be a split decision but that’s all Biden needs. His blunders, his aides say, are baked into the cake and he benefits massively from the priceless presumption that he possesses the ability to defeat Donald Trump. It’s self-perpetuating: As long as Biden stays atop the polls, he’s electable. He’s electable because he sits atop the polls.

The person most alarmed about Democrats questioning Biden being up to the job is attorney George Conway, a Never Trumper a.k.a. the husband of Always Trumper Kellyanne Conway. “We have an incoherent president who’s off his rocker,” Conway tweeted after Ryan and Rendell’s concerns about Biden came out, “and this is what we’re talking about? Seriously?”

Conway’s question puts Biden’s debate performance in perspective. Biden’s faulty memory, shaggy dog stories, remembering the past the way he wishes it was—yes, those are problems, but compared to what? Trump lies to get out of trouble and just for the heck of it, as he did about Dorian striking Alabama, when there’s a map to prove it wouldn’t and a few honest civil servants unafraid to say so, despite their jobs being threatened. Biden is a whole man and Trump is a broken one, damaged in ways we can’t imagine, rendering him unable to form normal relationships, keep friends or staff, sit still long enough to know not to bring terrorists to Camp David, or to make informed decisions on making, or ending, a war. He’s a sexual predator who says lewd things about his daughter. He’s corrupt to his core and he’s corrupted the Air Force and Mike Pence to divert taxpayer money to his hotels.

Trump’s lies hurt us; Biden’s mistakes hurt him.