The last thing former vice president Joe Biden said from the debate stage on Wednesday night was an exhortation for people to join his campaign.

Americans working together, he said, had always been able to overcome obstacles.

“If you agree with me,” he continued, “go to Joe” — he paused, very briefly — “three-oh-three, three-oh and help me in this fight.”

He’d meant to say that you should text the word “Joe” to that number, not go to that website. (A version of that domain was quickly purchased by the campaign of South Bend, Ind., Mayor Pete Buttigieg.) The result? A muddled, confusing close to what should have been one of the easiest parts of his pitch, a memorized statement.

Biden’s performance overall was shaky. He was at times prepared, as when Sen. Kirsten Gillibrand (D-N.Y.) came at him about past comments about women in the workplace. At other times, he seemed to fumble with facts or to demurely stop speaking when his time was up — which for a presidential candidate is like President Trump deciding against complaining about things on Twitter.

He was also battered repeatedly, to varying degrees, by the other candidates. His joking comment upon greeting Sen. Kamala D. Harris (D-Calif.) — who, in the last debate, had leveled Biden on the issue of busing — was that he hoped she’d go easy on him. She didn’t, nor did any of the other candidates. This time around, though, it wasn’t Harris who got in the most effective blows; that was Sen. Cory Booker (D-N.J.), who batted away Biden’s rejoinders about criminal justice like Neo in “The Matrix” marveling at incoming bullets. Even New York Mayor Bill de Blasio (D) scored several goals on Biden, and he’s the least-liked candidate in the field.

Fine. A wobbly debate performance. Every candidate has those. When President Barack Obama stumbled in a debate in 2012, pundits wondered if he could possibly recover. He did, earning another four years for Biden to talk about.

But it’s impossible to forget that Biden’s sales pitch is explicitly that he’s the guy who won’t stumble. He’s the guy who will bring the fight to that schoolyard bully Trump. He’s the guy willing to scrap, to go toe-to-toe. And then he gets into the ring in some warm-up fights against other Democrats and comes out with a bloody nose and a grin that’s missing two teeth.

This probably won’t really matter. Biden has three things going for him, of which a sense of electability is only one. The other two are his strong grip on moderate Democrats — aided by the fact that more progressive candidates are splitting the pool of liberals — and strong support from black Democrats. That support is bolstered by the other two positives Biden enjoys. Black voters tend to be more moderate, and most Democrats see Biden as the best candidate against Trump.

When Harris knocked him to his knees last month, that perception wavered. Polling from Quinnipiac University saw views of Biden’s electability plunge after that first debate, only to recover earlier this week as the negative effects of his first performance wore off. Harris surged after that first debate, but that surge faded.

The question is whether Biden can keep surviving getting knocked to his knees. How many more performances like this can his poll numbers weather?

It’s quite possible that the answer is “all of them.” Biden’s electability stems in part from polls that show him beating Trump, a pretty difficult bit of data to argue against, however self-fulfilling it might be.

It’s also possible that the answer is “not many more.”

In that first debate, there was a clear beneficiary of Biden’s ill fortunes: Harris. Juxtaposing Biden’s performance against hers offered a stark contrast. This time, it’s a bit murkier. Booker landed a number of punches, but none as effective as Harris’s. Overall, Biden was probably a bit less composed than he was last time, but those things are easy to wave away. All of which is to say that this wobbly evening might not have long-term consequences.

Biden probably benefits from the fact that Trump himself sucks up so much media attention. One of the known weaknesses Biden had coming into the 2020 race was his tendency to misspeak or trip over his own feet. We’ve seen some flashes of that during the debates, the events in which the most eyes are trained on him. There have been other comments — his reference to working with a noted segregationist, for example — which burbled to the surface, too. For Biden, staying just out of sight as polls trickle in showing him beating Trump might be the best strategy.

He won’t be able to stay out of the spotlight forever. There’s a debate every month this year and, each time, he’ll face the same situation: lots of eyes, lots of opponents.

To put a fine point on it: Biden had a prepared closing comment that included a critical pitch for people to engage with his campaign. He flubbed that pitch and didn’t realize he flubbed it enough to correct the record in real time. It was the end of a long night, certainly. It is not, however, a lot to ask of a presidential candidate.

There are lots of these little cracks. Maybe they’re small enough to let Biden coast through the primary. Heck, they may be small enough to get him past Trump, a candidate who has more cracks than the land over the San Andreas Fault.

Or maybe it will all come apart.