Former Vice President Joseph R. Biden Jr. jammed his finger skyward, eyes narrowing like his polling advantage, accusing the “socialist” to his right, Senator Bernie Sanders, and the “distinguished friend” to his left, Senator Elizabeth Warren, of hawking infeasible health care proposals loaded with dubious math.
Mr. Sanders, raspier than usual but no gentler on audio equipment, insisted that Mr. Biden has “got to defend” a system that bankrupts cancer patients, drawing a steely glare from a front-runner well-versed in the disease’s ravages.
Mayor Pete Buttigieg tried to play the peacekeeping millennial, cutting in after Julián Castro — the former federal housing secretary disinclined to leave the squabbling to the three favorites — interjected from the stage’s periphery to suggest that Mr. Biden, well into his 70s, had forgotten what he said just two minutes prior.
“This is why presidential debates are becoming unwatchable,” Mr. Buttigieg said. “This reminds everybody of what they cannot stand about Washington.”
“Yeah, that’s called the Democratic primary election,” Mr. Castro shot back. “That’s called an election.”
It is getting there.
Onstage together for the first time, with less than five months to go before the voting begins, the top 10 candidates made clear on Thursday that the moment for oblique contrast and above-the-fray wishcasting is quickly passing. For the favorites, the new urgency yielded the most conspicuously fractious forum yet to air the central divide in the race: whether Mr. Biden’s beat-Trump-now-make-change-later relative incrementalism holds more appeal than the structural upheaval promised by Ms. Warren and Mr. Sanders.
Yet less than a year after Democrats’ midterm election success led, often, by the kinds of young and nonwhite voices the party has long prided itself on elevating — and of whom there was no shortage on the stage — the debate highlighted an uncomfortable truth: The top three candidates are all white septuagenarians, potentially hampering a generational argument against Mr. Trump.
For the seven other candidates in Houston — to say nothing of the more than a dozen others who have either dropped out or failed to qualify for this debate — the heightened testiness implied a determination to break through or deliver on their early promise as the campaign enters an unforgiving phase of field-culling and relevance-seeking.
Some tossed out jokes at their own expense. “I’m the only one who finds Trudeau’s hair very menacing,” said a shiny-scalped Senator Cory Booker, cracking about the well-coiffed Canadian prime minister. Mr. Buttigieg said, of his time serving in Afghanistan: “You know, I served under General Dunford, way under General Dunford.” Senator Amy Klobuchar came armed with one-liners: “He is treating our farmers and our workers like poker chips in one of his bankrupt casinos,” she said of Mr. Trump.
And Mr. Castro was eager to lash Mr. Biden over his age and his efforts to “take credit for Obama’s work, but not have to answer to any questions” about his administration’s record.
It is still early in the race, these campaigns all say. There is still time. But it is also not so early.
Many Democrats have been hopeful that defeating an unpopular, rampaging president would be as simple as nominating a sentient adult with minimal political baggage.
Though Mr. Biden, Ms. Warren and Mr. Sanders — and lower-polling candidates like Senator Kamala Harris and Mr. Buttigieg — have outpaced President Trump in some hypothetical general election surveys, party officials are cleareyed about the potential vulnerabilities dogging any of the present favorites.
In certain moments — and Thursday supplied a few — it can be difficult to imagine any of the current front-runners transcending their liabilities to become the nominee. Can Mr. Biden, nostalgic and blunder-prone, really convince an anxious party that he is a man in tune with the times? Can the Brooklyn baritone of Mr. Sanders really move the masses to the political revolution he promises? Can Ms. Warren erase voters’ concerns, sometimes whispered even at her own rallies, about her general election viability?
“There’s just a real anxiety about not making a mistake,” said David Axelrod, the former chief strategist to President Barack Obama, citing the party’s angst about defeating Mr. Trump. “That may raise the sensitivity to people’s potential liabilities. But I think what campaigns are about in certain ways is to put these theories to the test and explore people’s strengths and weaknesses and see who emerges. In 2007, there still was this chatter about ‘can Obama actually win a general election?’”
Mr. Biden and the two progressive senators are making radically different bets on the electorate.
“There’s enormous, enormous opportunities once we get rid of Donald Trump,” Mr. Biden said in his opening, before pledging to build on the Affordable Care Act, unlike rivals who prefer a “Medicare for all” system.
“Let’s be clear,” Ms. Warren said in one exchange with Mr. Biden, joining Mr. Sanders in suggesting that the former vice president was not being bold enough, “I’ve actually never met anybody who likes their health insurance company.”
But the three do share some surface similarities as prospective opponents for Mr. Trump, aside from their age. They are all veterans of the public eye, their weaknesses familiar to many Americans. And they have all been underestimated at various points in this primary, their manifest campaign warts — Mr. Biden’s gaffe-making, Ms. Warren’s fraught history with Native American ancestry, Mr. Sanders’s competition from Ms. Warren for liberal hearts and minds — misdiagnosed as politically lethal.
For Mr. Biden and Mr. Sanders, a clash at center stage was perhaps inevitable. Over their decades in Washington, they have taken radically divergent paths to the top of Democratic politics.
Mr. Biden has played the unrepentant insider, firm in his belief that making change is a matter of gradual progress and warm relations with ideological foes. And Mr. Sanders has been the unkempt agitator, long convinced that his uncompromising liberalism would take hold through sheer force of organizing.
Ms. Warren in some ways has instincts that fall between those two outlooks, pushing for “big, structural change” but also identifying as a capitalist and making overtures to Democratic Party leaders.
Yet until Thursday night, Ms. Warren, who is rising in the polls, had not yet faced serious scrutiny on the debate stage from her most prominent rivals.
That changed as a host of more centrist candidates ripped into some of the proposals she supports, especially “Medicare for all.” But Ms. Warren was often unruffled. She largely avoided being drawn into extended back-and-forths with her opponents, responding to overt and implicit criticisms by hewing closely to the populist progressive pitch she often makes on the trail, while also speaking in personal terms about her background.
“I wanted to be a public-school teacher,” she said. “And I invested early, I used to line my dollies up and teach school. I had a reputation for being tough but fair.”
Ms. Harris, who spent the first two debates locked in several heated exchanges with Democratic opponents, sought in the third debate to bring the focus back to defeating Mr. Trump, an effort she began in her opening statement and returned to throughout the evening.
“The only reason you’ve not been indicted is because there was a memo in the Department of Justice that says a sitting president cannot be charged with a crime,” Ms. Harris said, addressing Mr. Trump in her first moments onstage. She pledged to focus on “our common issues, our common hopes and desires and in that way, unifying our country, winning this election and turning the page for America. And now, President Trump, you can go back to watching Fox News.”
Later, in an exchange about trade, she compared Mr. Trump to the Wizard of Oz.
“When you pull back the curtain, it’s a really small dude,” she said.
“O.K., I’m not even going to take the bait,” replied George Stephanopoulos, the moderator, who stands at about 5-foot-5.
“Oh, George. It wasn’t about you!” she exclaimed.
There were areas of broad agreement on issues such as the need to combat gun violence, even if there was not a universally shared view on specific policies such as mandatory buybacks of assault rifles. And several of the candidates used foreign policy and trade to draw biting contrasts with the Trump administration.
Toward the end of the evening, Mr. Biden was pressed on a controversial statement he had made decades ago about race. He offered a meandering response, preaching the importance of exposing young children to as many words as possible.
“Play the radio, make sure the television — excuse me, make sure you have the record player on at night," he said.
Any children who tuned into the debate, too, were likely to have heard many words by the time it concluded — at least, those who watched the whole thing.
It lasted nearly three hours, ending just before 11 p.m. Eastern.