The former vice president had been asked to address recent comments he made promising not to demonize the wealthy but instead ducked it to discuss what he wants to do. Vermont Senator Bernie Sanders, meanwhile, said he would raise taxes on the wealthy and even on the middle class to pay for his Medicare for all plan.

“Yes they will pay more in taxes but less in health care for what they get,” he said. The back-and-forth came early on at the second night of the first debate of the Democrats’ presidential nominating process, as party voters begin to get a clearer view of the ideological choices they’ll face in caucuses and primaries early next year.

The candidates on the stage quickly got into testy exchanges, talking over each other, until Senator Kamala Harris stepped in.

“America doesn’t want to witness a food fight, they want to know how we’re going to put food on their tables,” Harris said, putting an end to the squabble.

Thursday night’s debate in Miami was the first side-by-side appearance of the campaign for Biden and Sanders, and the contrasts between the two are being carefully watched as they chart starkly different paths to the party’s nomination and beyond that, the 2020 general election.

Sanders, an independent senator from Vermont, has already begun highlighting where he diverges with Biden, aiming to expose the former vice president’s weaknesses with left-leaning voters on issues such as Medicare for All and the Green New Deal.

The debate is giving voters a chance to see four of the five top-polling candidates for the Democratic nomination interacting with one another, plus half a dozen candidates who’ve averaged 1% or less in key state and national polling.

Biden and Sanders, two white male septuagenarians, are positioned at podiums in the middle of the stage, flanked by younger, more diverse opponents.

On one side is the 37-year-old openly gay mayor of South Bend, Indiana, Pete Buttigieg, and on the other is Senator Harris of California, 54, an African- and Indian-American woman.

Massachusetts Senator Elizabeth Warren, who’s edging out Sanders for second in a growing number of polls, was the only candidate among the leading contenders who ended up on Wednesday’s debate stage.

Warren’s lower-polling rivals did nothing to knock her off course or didn’t challenge her attempt to overtake Sanders as the strongest alternative to Biden. That allowed her to stick largely to her stump speech and deliver a progressive message to millions of people on everything from the corrosive effect of corporate money to gun control, without getting distracted or having to react to a sharp retort.

Representing the Democrats’ centrist wing, Biden, 76, represents a target for Sanders, 77, who’s running on a platform he describes as democratic socialism. As the clear leader in polls at this early stage of the race,

Biden also is in the sites of the other eight candidates on the stage, who’ve been delivering their critiques of him for weeks even as they avoid attacking him directly.

Trump Effect

There was little discussion of Trump during Wednesday’s debate, but with Biden and Sanders more explicitly building their campaigns around their arguments of electability the president was a more central foil on Thursday.

The president, who’d suggested he may live-tweet the debates, posted just twice on Wednesday, complaining that the event was “BORING!” and about host network NBC’s technical difficulties.

During Thursday’s event he’ll presumably be out of pocket at the start of a long day of bilateral meetings at the Group of 20 summit in Osaka, Japan.

Wednesday’s event drew a total of 15.3 million viewers, according to Nielsen data cited by NBCUniversal, to be the most-watched TV program of the night.

Ratings were dwarfed by those of the first Republican deb ate of 2015, when 24 million viewers tuned in to watch Trump spar with moderator Megyn Kelly.

Chance for Opening

While the first round of debating isn’t likely to shake up the race, a handful of middle-tier candidates including New Jersey Senator Cory Booker and former Housing and Urban Development Secretary Julian Castro were able to breathe new oxygen into their bids with strong performances on Wednesday night.

Senators Kirsten Gillibrand of New York and Michael Bennet,of Colorado, as well as former Colorado Governor John Hickenlooper, all of whom rarely crack 1% in polls, may be hoping to do the same on Thursday.

Elevator Pitches

The stage tonight also features two candidates who have never held elected office: former tech entrepreneur Andrew Yang, whose core promise is to establish a universal basic income of $12,000 for every American adult, and spirituality author Marianne Williamson.

The candidates won’t have much time to make their cases, with no opening statements, 60 seconds to answer questions, and 30 seconds to respond to attacks. A crew of five moderators from NBC, MSNBC and Telemundo on Wednesday held candidates closely to their time limits, though they did allow some candidates to interject as others spoke and for a handful of brief back-and-forths between pairs of contenders.

Moderators directed a disproportionate share of early questions to Warren on Wednesday and could do the same Thursday with Biden and Sanders, and perhaps also Buttigieg and Harris.

More must-read stories from Fortune:

—Harris has a strong showing, stuns Biden on night 2 of Democratic debate

—Democratic debate night 1: What we learned from each candidate

—2019 Democratic debate night 1: Highlights

—2019 Democratic debate night 2: Highlights

—Fact-checking claims from night 1 of the Democratic debate

—Fact-checking claims from night 2 of the Democratic debate