They did it without mentioning the 76-year-old front-runner at all. Biden, in turn, didn't mention them either. California Sen. Kamala Harris charged straight at Trump as she addressed hundreds of activists at the South Carolina Democratic Party Convention.
"We need somebody on our stage when it comes for that general election, who knows how to recognize a rap sheet when they see it and prosecute the case," Harris said, playing off her experience as a state and local prosecutor as she shredded Trump on a litany of policy fronts.
Then, in a seeming reference to Biden, the 54-year-old senator added that South Carolina voters mustn't "turn back the clock" but instead, "Let's start the next chapter. Let's turn the page." It was a demonstration that Biden, who's drawn fire in recent weeks for his reversal on opposing taxpayer funding of abortion and his recollections of working with long-dead segregationist senators, won't become the Democratic nominee without an intense fight, no matter his front-runner's strategy.
Massachusetts Sen. Elizabeth Warren pitched her progressive policies as an agenda with wide reach. "People across this nation understand it is time for big, structural change in America. The time for small ideas is over," Warren said, adding the approach can draw in Democrats and Republicans."
Vermont Sen. Bernie Sanders, meanwhile, pushed back at a centrist Democratic group, "Third Way," and some of its members' assertions that his democratic socialism is an "existential threat" to the party's 2020 hopes.
Sanders countered that his left-flank agenda can win the White House. "We defeat Trump by running a campaign of energy and enthusiasm that substantially grows voter turnout ... in a way we have never seen," he said.
Biden had the luxury of the last word Saturday, using his draw as the last of 20 candidates at the rostrum to deliver a rapid-fire litany of policy proposals, including a new pitch for an $8,000 tax credit for child care services.
The former vice president avoided mention of his recent spat with New Jersey Sen. Cory Booker, who'd called for the former vice president to apologize after recalling how he had to work with virulent segregationists when he was first elected to the Senate in 1972. Booker took particularly exception to Biden noting that Mississippi Sen. James Eastland "never called me boy," only "son."
In an interview with MSNBC after his speech Saturday, Biden did not apologize, saying his remarks got twisted. "I do understand the consequence of the word boy, but it wasn't said in any of that context at all," Biden says.
Biden said he was trying to illustrate that Eastland didn't respect him, then the youngest senator. Biden has said he mentioned the segregationists in the first place only to underscore that Congress once functioned better than today even with men like Eastland in the mix, because members worked together despite fundamental disagreements.
The convention Saturday was part of big political weekend in South Carolina that also included a Friday night party gala; the annual fish fry hosted by House Majority Whip Jim Clyburn; and a Saturday forum hosted by Planned Parenthood.
For South Carolina Democrats, it was the culmination of several decades raising the state's profile to compete with Iowa and New Hampshire, the two states that for decades have led off presidential voting. For Biden and his rivals, it was a key test in a crucial primary state and a last public tune-up ahead of next week's inaugural 2020 debates in Miami.
South Carolina boasts the largest electorate of the four early nominating states, and its mix of black voters and moderate whites gives candidates a proving ground ahead of a Super Tuesday slate of similar Southern states with hundreds of delegates at stake.
Biden has led national Democratic polls since he announced his bid in April. He has shown particular strength in South Carolina, where he has deep relationships from previous presidential runs, friendships with two of state's towering former senators and, perhaps most important in 2020, his eight years as President Barack Obama's vice president.
The South Carolina crowd roared when Biden mentioned his old boss and compared his demeanor to Trump's. "Our children are watching, they're watching, and it matters what presidents say and do," Biden said. "Barack Obama they watched, and they emulated. They wanted to be like him."
The wide-ranging arguments in response revealed a Democratic field without a settled counter to the front-runner's early advantages. But it was clear that Biden's rivals won't yield South Carolina or the Super Tuesday map.
Minnesota Sen. Amy Klobuchar, who campaigns heavily on her electoral success in Midwest states that swept Trump to office, tried to apply that to Republican-run South Carolina. "I know how to win," she said.
Mayor Pete Buttigieg of South Bend, Indiana, made his first appearance of the weekend on Saturday, a white politician whose relationships with black constituents are in the spotlight. Buttigieg had canceled his Friday plans in South Carolina to remain at home after a South Bend police officer shot and killed a black man last weekend.
"We will heal and we will become stronger in the broken places," Buttigieg promised on the morning after he was jeered in his hometown. Buttigieg later promised massive investments in the black community on the scale of the Marshall Plan in post-World War II Europe.
Follow the reporters on Twitter at https://twitter.com/BillBarrowAP and https://twitter.com/MegKinnardAP .