Former Vice President Joseph R. Biden Jr.’s presidential campaign has been defined by what it’s not as much as by what it is. He hasn’t made waves with big-ticket policy proposals, and he has mostly avoided skirmishing with his Democratic rivals.
And so, nine months into his campaign, Mr. Biden is in a remarkably similar position to where he was when he began: He’s the presumptive front-runner, despite a lack of agenda-setting plans or breathless enthusiasm from supporters.
Poll results can help us understand why. For one thing, Democratic voters appear to want a candidate who they think has a good chance of beating President Trump more than one whose policy views sync up perfectly with their own.
In a Monmouth University poll last month, this question was put to likely Democratic primary voters nationwide: Would you prefer a strong nominee who could defeat Mr. Trump, even if you disagree with that candidate on most issues — or a candidate with whom you see eye to eye, but who would have difficulty overcoming the president?
Almost twice as many respondents chose the candidate with a better chance of winning.
Polls suggest that Mr. Biden’s support is built largely on these very voters, who are seeking an experienced leader to reverse the Trump administration’s policies.
In a CNN poll last month, 40 percent of likely Democratic voters who responded said they thought Mr. Biden would be the strongest candidate against Mr. Trump. Only 16 percent pointed to Senator Bernie Sanders of Vermont, Mr. Biden’s closest rival.
Democrats across demographics tend to agree that beating Mr. Trump is the main priority. As a result, Mr. Biden has built a remarkably broad coalition of voters, with support cutting across race, gender and educational background.
But a degree of insecurity still lingers. The former vice president has faced strikingly few challenges from his rivals or from debate moderators in recent months — a boon to his candidacy that could evaporate if his opponents’ tactics change.
“A core part of his support has never been driven by enthusiasm for him — it’s driven by a sense that he’s the safe choice,” said Patrick Murray, the director of the Monmouth University Polling Institute.
“Unlike Sanders, whose core support is very much gung-ho for him and knows what they signed up for, Biden’s supporters are looking for the strongest candidate,” Mr. Murray added. “He has so far survived that examination, but that doesn’t mean it can’t change over the next few weeks.”
Indeed, Mr. Biden’s support dipped for weeks in the fall amid a surge from Senator Elizabeth Warren of Massachusetts, who was seen as possibly more capable of uniting the moderate and left wings of the Democratic Party. But her polling numbers began to waver after her support for “Medicare for all” drew criticism, and much of Mr. Biden’s support appeared to stabilize.
Democratic voters have grown more liberal over the past two decades, but moderates now feel more alienated from an increasingly ideological Republican Party than they did a generation ago. As a result, moderate voters still tend to lean Democratic, and they make up a big enough share of the party to play a decisive role in choosing its nominee.
“You have a lot of Democrats who are not beholden to an ideological position but feel comfortable with him,” Mr. Murray said of Mr. Biden. “They’re coming from all walks of life.”
About as many women support Mr. Biden as do men, and he is the most popular candidate among black Democratic voters — a key constituency, particularly in the primaries. (Mr. Sanders has encroached on that lead, however, and now trails by less than 10 points among African-American voters and other nonwhite voters, according to some national polls.)
Just as crucially, Mr. Biden’s numbers are as strong among white voters without college degrees as they are among those with a higher education. That puts him at a distinct advantage over Ms. Warren and Pete Buttigieg, the former mayor of South Bend, Ind., two of his strongest opponents.
And while Mr. Biden’s supporters tend to be slightly more moderate than other candidates’ backers, they are generally paying attention to the same issues. They are most likely to list health care as their main policy concern, with climate change second, according to a Quinnipiac University poll released this week. Those results are consistent with the party’s voters at large.
Mr. Biden has also benefited from the fact that Democrats are far more likely than Republicans to be looking for a leader with solid political experience, according to a multilevel analysis of voter preferences published this month by Monmouth. Mr. Biden, who was first elected to the Senate 48 years ago, is by far the most popular candidate among Democrats who prioritize experience in a nominee: Forty-four percent of such voters back him, the Monmouth analysis found.
Finding an experienced leader matters particularly to voters of color, especially women of color, the study found.
And if he does not rack up decisive victories in the earliest-voting states over the coming two months, he could be vulnerable to the growing challenge of Michael R. Bloomberg, the billionaire former mayor of New York City, who entered the race in late November and is not competing in the earliest states.
Polls show that Mr. Bloomberg is strongest among older voters, black people and moderate or conservative Democrats — all crucial elements of Mr. Biden’s coalition.