Hi, and welcome to a special post-debate edition of On Politics. I’m Lisa Lerer, your host.

After months of volatility, the Democratic primary coalesced into a steadier pattern this summer: a two-tiered race, with former Vice President Joe Biden, Senator Elizabeth Warren and Senator Bernie Sanders at the top, followed by a slim second tier.

And, after that, a whole lot of people who probably don’t have much of a shot at actually becoming president. (Sorry, folks!)

Last night’s debate didn’t appear to change that dynamic.

Yes, Mr. Biden occasionally lapsed into word salad with a dressing of mixed metaphors. An answer on racial disparities in education moved through institutional segregation, school psychologists, teacher pay, and his current and late wives, and ended, somewhat confusingly, by urging parents to keep a record player on at night for the sake of their children. Then, he pivoted to Venezuela. “Well, that was quite a lot,” said Julián Castro, the former housing secretary, when his turn came.

But Mr. Biden survived a flurry of attacks on his health care plan, his vote for the Iraq war, trade policy and even his age. He energetically went after Ms. Warren and Mr. Sanders for supporting a “Medicare for all” health care system, and shrugged off a fairly clumsy shot by Mr. Castro aimed at elevating persistent whispers about his mental fitness.