(Bloomberg) — Democratic presidential candidate Joe Biden on Wednesday urged his opponents to keep the race positive as it intensifies, an implicit rebuke of Bernie Sanders’s aggressive response to the former vice president’s Super Tuesday victories.“What we can’t let happen is let this primary turn into a campaign of negative attacks,” Biden said in a brief statement to reporters in Los Angeles. “The only thing that can do is help Donald Trump and it doesn’t do anything to help any one of the candidates who are left in the campaign.”Earlier Wednesday, Sanders, who underperformed polling and expectations in many of the 14 states that voted on Tuesday, released three negative ads about Biden.In a brief appearance before the press in Burlington, Vermont, Sanders accused “the political establishment” of trying to destroy his campaign and said Biden’s campaign was backed by corporations and funded by billionaires.While Biden did not directly address Sanders in his prepared statement, he took aim at his rival in response to a reporter’s shouted question.“The establishment are all those hardworking, middle-class people, those African Americans, the single women in suburbia. They’re the establishment,” Biden said, referring to the voters who turned out for him at record levels in some states.In a tweet, Sanders replied: “No, Joe. The ‘establishment’ are the 60 billionaires who are funding your campaign and the corporate-funded super-PACs that are spending millions on negative ads attacking me.”On Monday evening, the Biden campaign said it had raised $7 million from online donations since Super Tuesday, while the Sanders campaign said it had taken in $5.5 million from 220,000 donors in the same time period.Biden won 10 of the 14 states that voted on Super Tuesday and opened up a delegate lead over Sanders, who won his home state of Vermont, along with California, Utah and Colorado.Elizabeth Warren, failed to win a single state, including her home state of Massachusetts, and campaign manager Roger Lau said Wednesday she is assessing the future of her candidacy. Her withdrawal would virtually ensure a two-person race between Sanders and Biden, given the weakness of the sole other remaining contender, Tulsi Gabbard.The former vice president benefited from the decision of Pete Buttigieg and Amy Klobuchar to drop out of the race and endorse him just before Tuesday’s votes. He’s received plentiful endorsements in recent days from current and former members of Congress, as well as members of the Obama administration.Biden also used his appearance, his first since Tuesday, as a chance to look ahead, not just to the general election but to a potential presidency, promising that he would continue to unveil more policy plans in the months ahead.Biden asked voters who’d supported other Democratic hopefuls or were undecided to join him.“We welcome all those who want to join us. To build a movement, and this is a movement we’re building. And we need that movement to defeat Donald Trump,” he said.(Updates with fundraising totals, in eighth paragraph.)To contact the reporter on this story: Jennifer Epstein in Los Angeles at [email protected] contact the editors responsible for this story: Wendy Benjaminson at [email protected], Max Berley, John HarneyFor more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.