LOS ANGELES — Two leading Democratic presidential contenders, Elizabeth Warren and Pete Buttigieg, clashed over campaign fund-raising as a shrinking group of candidates met on the debate stage Thursday for the sixth and final time in 2019.

The face-off among the seven Democratic candidates was substantive and civil early on, but sharpened in the second hour of the prime-time debate.

“Most of the people on this stage run a traditional campaign, and that means going back-and-forth, coast-to-coast to rich people," Warren said in a jab at Buttigieg, noting that he recently met privately with donors inside a California “wine cave,” as noted in a recent Associated Press story.

“Billionaires in wine caves should not pick the next president of the United States," she charged.

Buttigieg, who has surged into the top tier of the Democratic Party’s 2020 primary in part because of his fund-raising success, did not back down.

“We need to defeat Donald Trump,” he responded. “We shouldn’t try to do it with one hand tied behind our back.

Support for President Donald Trump’s impeachment and criticism of his economy dominated the early moments of Thursday night’s debate with the Democratic Party’s leading presidential contenders.

The Democrats' debate — the sixth in the cycle — was set in the heart of the holiday season just a day after the House's historic vote to impeach Trump, raising the prospect that it may draw the smallest audience yet. But the stakes were not small in the broader tug-of-war between passionate progressives and pragmatic moderates who are battling over the party's positions on core issues like health care, immigration, education and trade.

Despite the potential for intraparty discord, the early moments of Thursday's debate highlighted the Democrats' shared criticism of the Republican president's vision for America.

“The president is not king in America,” said Minnesota Sen. Amy Klobuchar, who is preparing to serve as a juror as Trump's impeachment shifts from the House to the Senate. Alluding to President Richard Nixon, she added, "If the president claims that he is so innocent, then why doesn't he have all the president's men testify?"

Former Vice President Joe Biden knocked Trump's argument that less than half of Americans support his removal from office.

“He's dumbing down the presidency beyond what I even thought he would do,” Biden said. “We need to restore the integrity of the presidency.”

The candidates also railed against Trump's economy, despite outward indicators that the economy is doing well.

The U.S. unemployment rate stands at a half-century low of 3.5%, backed by consistently strong job gains in recent months that have largely squelched fears of a recession that had taken hold over the summer.

“This economy is not working for most of us," said Buttigieg, the mayor of South Bend, Ind.

"The middle class is getting killed,” Biden added.

Warren and Buttigieg entered the night at the center of the high-stakes clash.

Warren, a 70-year-old Massachusetts senator, has fought for transformative policies to limit corporate influence on the nation’s political and economic systems for more than a decade. Buttigieg, 37, has emerged as a strong, if surprising, face of the party’s more centrist wing as he navigates his connections to corporate America, both in his work history and as a presidential fund-raiser.

Diversity — or lack thereof — onstage is also prominent. The Democratic field is marked by wide differences in age, geography and wealth, but Thursday’s group doesn’t feature a black or Latino candidate for the first time this year. Entrepreneur Andrew Yang, who is Asian American, is on stage.

The state of play on the ground in California has largely mirrored national trends, with former Biden, Vermont Sen. Bernie Sanders and Warren clustered at the top of the field, followed by Buttigieg, Klobuchar, Yang and billionaire philanthropist Tom Steyer.

Associated Press writer Michael R. Blood contributed to this report from Los Angeles.