Does the road to the White House run through a wine cave?

That was the question that electrified the Democratic debate in Los Angeles on Thursday. It was specific, referring to the location of a recent fundraiser that Pete Buttigieg had held in Napa Valley.

But it was also metaphoric, a stand-in for the wider argument among Democrats over pragmatism versus purity, compromise versus idealism, a candidate like Buttigieg or Joe Biden versus a candidate like Elizabeth Warren or Bernie Sanders.

As Warren blasted Buttigieg for kissing up to wealthy donors — and he portrayed her as an unpractical hypocrite — they weren’t really sparring over cabernet and cash. They were promoting separate strategies for winning the presidential election, different ways to position their party and vanquish Donald Trump.

It was the same conflict that has defined the Democratic primary from the start, but with extra fury. Passions often burn hotter when alcohol is involved.

“Billionaires in wine caves should not pick the next president of the United States,” Warren said, exploding the relative politeness of the debate to that point.

Buttigieg was ready for this, noting that she’s actually a millionaire — several times over — and he’s not. “Senator, your net worth is 100 times mine,” he said. So if she donated the legal maximum of $2,800 to him, he asked, “Would that pollute my campaign because it came from a wealthy person? No. I would be glad to have that support. We need the support of everybody who is committed to helping us to defeat Donald Trump.”

“I do not sell access to my time,” she shot back.

“As of when, Senator?” he said, pointing out that she began her presidential bid with financial reserves from a Senate race in which she had indeed held the “big-ticket fundraisers you now denounce. Did it corrupt you, Senator? Of course not.”

They both had solid points. They both articulated them forcefully. In fact, they were both terrific, although less so during that exchange than during other stretches of the evening, as they made utterly clear why they are firmly ensconced, along with Biden and Sanders, in the top four.

That’s the hell of this primary: There’s talent galore. But with each talented candidate comes serious shortcomings, and there’s just no clear answer to which of them — including Amy Klobuchar, who had an excellent evening and grows more and more appealing — would be Trump’s fiercest adversary.

The president was a bigger presence at this sixth Democratic primary debate than at the previous five, and that was inevitable. Just 24 hours before it began, he became the third president in American history to be impeached, a reflection of just how unfit for office almost all Democrats rightly deem him to be.

But impeaching him won’t get rid of him; for that, beating him in November 2020 is necessary. So the debate was all about which candidate would ensure that, as all seven of those who appeared onstage gave their pitches.

Tom Steyer, a billionaire, noted that Trump would run on his economic record of low unemployment figures and a bullish stock market, so his opponent should be someone who could poke the right holes in that. Someone with irrefutable business acumen. Someone like, well, Tom Steyer.

Klobuchar, who represents Minnesota in the Senate, noted that the Midwest was crucial to Trump’s election, so his opponent should be someone with the proven ability to win votes there. Someone from the Midwest. Someone like, well, Amy Klobuchar.

Biden, the former vice president, stressed the importance of a leader with the experience to begin effective repair work and restore America’s leadership in the world right away. He also emphasized the need to at least take a stab at bipartisanship and did so in a fashion more heartfelt and gripping than ever.

“I refuse to accept the notion, as some on this stage do, that we can never, never get to a place where we have cooperation again,” he said. “If that’s the case, we are dead as a country. We need to be able to reach a consensus. And if anyone has reason to be angry with the Republicans and not want to cooperate, it’s me — the way they’ve attacked me, my son and my family.”

Buttigieg, the 37-year-old mayor of a small Indiana city, asserted anew that a fresh perspective from outside Washington was the answer.

This prompted the evening’s second most fiery exchange, between him and Klobuchar — who is in her third term in the Senate.

“When we were in the last debate, Mayor, you basically mocked the hundred years of experience on the stage,” Klobuchar said to him. “And I have not denigrated your experience as a local official.”

“You actually did,” he responded. “I was going to let it go, because we have bigger fish to fry here.”

“Oh,” she said, “I don’t think we have bigger fish to fry than picking a president of the United States.”

They proceeded to joust over whether he’d won tough elections, with him bringing up his challenges as a gay man. It was riveting and raw and a sign of how close the Iowa caucuses are drawing, how nervous Democrats are about finding the path to the end of Trump, how urgent all of this feels.

Warren leaned on “corruption” as hard as she’d leaned on “fight” during prior debates, insisting that corruption’s most ardent enemy would be Trump’s scariest foe. She also had the best line of the night, delivered when the candidates were being asked about recent remarks by President Barack Obama that took issue with how male, old or both many of the Democrats vying for the White House were.

“Senator Warren, you would be the oldest president ever inaugurated,” one of the moderators, Tim Alberta of Politico, said. She’s 70 now.

“I’d also be the youngest woman ever inaugurated,” Warren answered.

The second best line was Andrew Yang’s. Speaking up for more women in government, he said, “If you get too many men alone and leave us alone for a while, we kind of become morons.” But he added that the excessive importance of money in politics was a bar to female candidates, who aren’t poised “to go shake the money tree in the wine cave.”

His wit and Warren’s deftness were no surprise. Biden’s brio and confidence were.

He didn’t have the best debate of the night, because he can’t. Biden speaks not in straight lines but in wide swerves: If he were a car, his tires would constantly scrape the curb and his hubcaps would probably pop off.

But they stayed on this time, and he steered clear of danger, by which I mean the wine cave, acknowledging his own rich donors without investing himself in the kind of defense that Buttigieg was compelled to mount.

And in his zigging and zagging way, Biden recognized that what divides the race’s progressives from its moderates isn’t values but the candidates’ assessments of what can safely be promised and reasonably achieved.

I’ll drink to that. And in honor of “Joe Sixpack,” I’ll make it a beer.

Frank Bruni

Frank Bruni is an Op-Ed columnist for The New York Times.