THE THIRD Democratic primary debate held in Houston on September 12th had been billed as a battle of the big beasts. More stringent entry criteria meant this was the first time Joe Biden, Elizabeth Warren and Bernie Sanders appeared on stage together. Yet over the course of a three-hour—at times seemingly interminable—performance, the three front-runners only occasionally locked horns and none said anything that will obviously change his or her standing in the race by much.

Mr Biden, who has led by a healthy margin throughout, gave one of his better showings—though, given how poorly he had performed previously, that sets a low bar. He gave a solid-enough answer on health-care policy, contrasting his commitment to shoring up Obamacare with his left-wing rivals’ more radical promise of Medicare-for-all. In a concluding riff, he spoke movingly of the tragedies he has suffered—the loss of a wife and child in a car accident; the loss of a son to brain cancer—and asked his audience to reflect on the everyday sadnesses that preoccupy ordinary Americans. It illustrated why so many Democrats are fond of the 76-year-old former vice-president. But in between he often rambled and misspoke, sometimes incoherently. Not for the first time, this suggested he may not be the low-risk challenger to President Donald Trump that most Democrats seem to be looking for.

Asked about the legacy of slavery, Mr Biden bemoaned “institutional segregation”, noted that his living and late wives had both been teachers and argued forcefully that poor parents should leave a “a record player on at night” so their children could learn new words. He then added a bizarre digression on the state of Venezuela and, somehow, immigration policy, before issuing a finger-wagging warning to his rivals: “You’re all acting like we just discovered this yesterday!” “Well that’s—that’s quite a lot…” marvelled the next speaker, Julián Castro. A face-off between Mr Biden and Mr Trump—whose word salads are even stranger—would not raise America’s standard of political debate.

Ms Warren, who is Mr Biden’s closest rival, did not go after him as some had expected her to. The senator from Massachusetts makes a point of not attacking other Democrats. Despite some confident remarks on health care and one or two other favourite policy areas, she even drifted out of the debate altogether at times. Mr Sanders, though as ever an accomplished debater of his chosen economic issues, sounded weary and scored no new points.

The next best-placed candidates, Kamala Harris and Pete Buttigieg, also had unremarkable nights. The senator from California tried to reignite her stuck campaign with a few rehearsed one-liners, chiefly at Mr Trump’s expense. On trade policy, she chortled, the president reminded her of “that guy in ‘The Wizard of Oz’; you know, when you pull back the curtain, it’s a really small dude?” Not bad; Ms Harris can land a joke. Yet it is still not quite clear what her politics are. Whether they are moderate or more to the left, the ambiguity risks making her look calculating, even opportunistic. A grilling she received over her record as a tough-on-crime prosecutor in California appeared designed to underline that weakness. Mr Buttigieg, the cerebral mayor of South Bend, Indiana, is more of a natural; he is worth listening to on most subjects and almost never puts a word out of place. Yet his progress in the race has also stalled, most obviously because black voters—who seem likeliest to decide the outcome of the primary—have more qualms about gay politicians than do white liberals. It would be surprising if his precise, low-key performance in Houston had any effect on his poll numbers.

It was more remarkable to see how strongly several of the also-rans performed. Amy Klobuchar and Cory Booker, senators from Minnesota and New Jersey, delivered much sharper and more coherent centre-left pitches than Mr Biden. Mr Booker, who has shed some of his excessive earnestness, and is more appealing for it, also delivered the best gag of the evening. Asked by the debate moderator Jorge Ramos whether more Americans—“here in Texas and in Iowa”—should adopt his vegan diet, the senator deadpanned at the expense of his flashily Spanish-speaking rivals: “I want to say, no. Actually, I want to translate that into Spanish: no.”

One of those rivals, Beto O’Rourke, also had a decent evening. Pepped up by the attention his campaigning against gun violence has received following a slaughter in his hometown of El Paso last month, Mr O’Rourke was on fluent form. His insistence that military-grade weapons should be forcibly withdrawn from civilian ownership—a position that would make it hard for him to revive a state-level career in his native Texas—drew one of the biggest cheers of the night. If Mr Biden’s support were to collapse, as has often been predicted, it would not be surprising to see Ms Klobuchar, Mr Booker or Mr O’Rourke surge. Despite the relish almost all the candidates expressed for their policies—and for the often marginal differences between them—Democratic voters are mostly concerned to get rid of Mr Trump: a recent poll suggested that just 2.5% are mainly bothered about education—a big topic of the debate in Houston—while almost 40% just want to oust the president. And many fear Ms Warren and Mr Sanders are too left-wing to persuade the general electorate to do that.

Hence Mr Biden’s lead and his supporters’ reluctance, despite his poor performance on the trail, to abandon him. Yet this has made it almost impossible for a dozen or so lesser-known, but fresher and perhaps more imposing moderates, such as Ms Klobuchar and the rest, to get much of a hearing. Democrats may come to rue this. Debate performances are not great predictors of electoral success (let alone of a candidate’s chances of being a good president—about which they give almost no indication). Even so, it is slightly odd to see so many Democrats doggedly sticking with one of the weakest campaigners in their primary.