Biden has centered his campaign on his years of experience in Washington and a perceived ability to steal the support of white, working-class voters away from President Donald Trump. Speaking at the New Hampshire Democrats' state convention, Biden's rivals told voters to aim for more.
"There is a lot at stake and people are scared. But we can't choose a candidate we don't believe in because we're scared," said Sen. Elizabeth Warren, who drew a raucous reception. "And we can't ask other people to vote for someone we don't believe in."
Pete Buttigieg, the 37-year-old mayor of South Bend, Indiana, was more explicit. "Every time we've tried to play it safe with established and Washington-tenured figures, every single time we've come up short," Buttigieg told reporters after his remarks.
Warren, Buttigieg and others never mentioned Biden by name. But the target of their message was clear: the former vice president who has led primary polls throughout the year despite questions about whether a 76-year-old white man is best-positioned to be the standard-bearer for an increasingly diverse party.
Saturday's convention kicked off a critical stretch of the campaign in New Hampshire, which in February will hold the nation's first primary. Nineteen candidates descended on the state to rally voters and flex their campaign's organizational strength in front of New Hampshire's political power brokers, most of whom are still up for grabs.
Supporters for major candidates arrived outside the arena in Manchester before dawn to hang signs and stake out prime locations to greet the convention's hundreds of attendees. Warren's crowd of supporters stretched deep and erupted in cheers as the senator arrived to greet them. Rival campaigns grumbled privately that Warren, who represents neighboring Massachusetts, was benefiting from home-field advantage.
Much of Biden's strength in the race thus far is tied to the perception that he is best-positioned to defeat Trump, given his more moderate policies, working-class background and the reservoir of goodwill he built up with many Democrats during his eight years as Barack Obama's vice president.
But rival campaigns privately draw comparisons between Biden and Hillary Clinton, the 2016 Democratic nominee who was deemed the best-qualified candidate but struggled to generate high levels of voter enthusiasm. They argue that nominating Biden risks depressing the vote among energized liberals and younger voters.
Biden was the first candidate to speak and focused his remarks on Trump, saying the president has "unleashed the deepest, darkest forces in this nation." He added: "We cannot, and I will not, let this man be reelected president of the United States of America."
Former Housing Secretary Julian Castro said that if Democrats want to ensure Trump is defeated, "we can't do the same old thing." "We're not going to win by just trying to be safe," Castro said. New Jersey Sen. Cory Booker, who enlivened the crowd with his morning address, also urged voters to seek more than simply a candidate they believe can beat Trump.
"Beating Donald Trump is the floor, it's not the ceiling," Booker said. New Hampshire has a track record of humbling Democratic front-runners, and victory in the state has often not been an indicator of general-election success.
Since 1976, the year Democrat Jimmy Carter won the state's primary, no competitive New Hampshire Democratic primary winners have gone on to capture both the party nomination and the presidency. Warren and Vermont Sen. Bernie Sanders share the same advantage as neighboring senators to New Hampshire, though Warren has spent more days campaigning in the state than her presidential rival. Sanders remains a strong draw, something that was clear with the fervent welcome that greeted him as he took the stage for his convention speech Saturday afternoon.