On Friday, she was scheduled to begin a bus tour in Iowa, with stops in 27 counties in the state.

“Clearly Klobuchar believes she needs to go after Pete” to improve her position in Iowa, said Douglas Herman, a Democratic strategist in Los Angeles. “He is also at the top of the moderate lane in Iowa, so Klobuchar has to beat him with those voters.”

Given the short time until Iowa and the high stakes of performing well there, Herman said Klobuchar “needs to move further. Hence the persistent attacks on Pete whenever she could get an elbow toss in.”

After the debate, Buttigieg offered the predictable assessment of the beating he took, telling CNN that attacks should be expected “when you’re doing well.” And Dave Nagle, a former congressman and Iowa state Democratic Party chairman, suggested Buttigieg is a victim of his own, possibly too-early success.

“It’s not a good thing to get hot in November, because you become a target,” Nagle said.

But it wasn’t just the downtrodden of the Democratic field turning on Buttigieg. For top-tier candidates, the imperative to attack one another has been relatively low for months — and for good reason. In a multi-candidate field, the aggressor doesn’t always benefit from dragging down another candidate. Biden, in particular, has largely refrained from punching down.

But Sanders and Warren, both far ahead of Buttigieg nationally yet locked in a tight battle with him in Iowa, are increasingly using Buttigieg as a foil.

Seizing on the location of a Buttigieg fundraiser in Napa Valley this past weekend — in what Warren called a “wine cave full of crystals” — Sanders and Warren both launched an extended debate-stage assault on Buttigieg over his fundraising. Even Andrew Yang piled on, saying that with universal basic income, his signature proposal, more women would run for office “because they don't have to go shake the money tree in the wine cave.”

The hits are likely to get only harder going forward, as Buttigieg himself suggested in a fundraising email on Friday.

“Last night, I participated in the final Democratic primary debate of the year,” he wrote. “If you watched, you saw the campaign you and I are building come under attack.”