WASHINGTON – Bernie Sanders won New Hampshire’s Democrat primary with slightly more than one-quarter of the vote.

He has fewer delegates than Pete Buttigieg, the former mayor of South Bend, Indiana.

So why are many center-left Democrats worried that the self-described democratic socialist is the favorite to win the nomination?

Because there are too many candidates in the party’s center lane dividing up the rest of the vote.

“Every time a ‘moderate alternative’ fades, another emerges,” Dan Pfeiffer, who worked on Barack Obama’s 2008 campaign, said on his podcast the day after the New Hampshire primary. “In terms of delegate allocation, he’s in a very, very strong position.”

Other candidates have accelerated attacks on Sanders. He could end up a main target in Wednesday night’s debate in Nevada, where voting has begun for the caucuses that wrap up Saturday.

A poll taken this month by the Las Vegas Review-Journal shows Sanders leading the field in Nevada.

That causes consternation among some Democrats who say Sanders wouldn’t be as strong a general election candidate against President Donald Trump. There are also fears that a Sanders nomination could make it harder for the Democrats defending the swing congressional districts that won the party the House majority in 2018.

“I know that there’s a panic among some quarters of the Democratic Party about Bernie Sanders because he has a base and he has the resources to go on,” veteran Democratic strategist David Axelrod said on his podcast Wednesday.

Axelrod added that Sanders should be worried that he hasn’t shown he can grow his base.

“It’s hard to 25% your way to the nomination of the Democratic Party,” Axelrod said.

Before the voting began in Iowa this month, former Vice President Joe Biden had the strongest potential coalition – African Americans, white moderates and older voters – to defeat Sanders.

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Biden came in fourth in Iowa. He placed a dismal fifth in New Hampshire after losing moderates and older voters to Buttigieg and Minnesota Sen. Amy Klobuchar. National polls show a drop in Biden’s support from African Americans.

Matt Grossman, director of the Institute for Public Policy and Social Research at Michigan State University, said it’s far from clear that anyone else can reconstitute the potential winning coalition Biden had.

“Bernie is running 2nd among Black voters & 1st among other minorities,” Grossman tweeted Wednesday. “He is also the #1 2nd choice of Biden voters.”

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Democratic presidential candidate Bernie Sanders and his wife, Jane O'Meara Sanders, celebrate in Manchester, N.H., on Feb. 11.

Building a coalition

Buttigieg won the broadest support among different types of voters in Iowa and New Hampshire. In more racially diverse Nevada and South Carolina, which vote this month, Buttigieg will need more support from voters of color than polls show he’s getting nationally.

Klobuchar, likewise, hasn’t demonstrated strong appeal to African American voters.

That potentially leaves three scenarios, according to veteran Democratic strategists William Galston and Elaine Kamarck.

Enough backers of Biden and Massachusetts Sen. Elizabeth Warren could shift support to one of the top three finishers in New Hampshire – Sanders, Buttigieg or Klobuchar.

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Or former New York Mayor Michael Bloomberg, who is not competing in the first four states but is spending heavily in states that vote March 3, could emerge with enough support after Super Tuesday to take the lead.

There's also the chance the race remains a muddle all the way to June, and no candidate will receive a majority of the delegates before the national convention in July, Galston and Kamarck wrote in an analysis Wednesday.

That would be Democrats' first brokered convention in 68 years.

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Most Democrats are not 'liberal'

In the past 20 years, the share of Democratic and Democratic-leaning registered voters who describe themselves as “liberal” or “very liberal” has increased from 27% in 2000 to 47% in 2019, according to the Pew Research Center.

A slightly larger share of Democratic voters view themselves as moderate (38%) or conservative (14%).

“I’m a centrist Democrat. I’m not a progressive. I think some of the stuff he talks about is just financially unrealistic,” Steve Nadeau, a Biden fan from Massachusetts, said about Sanders. “It’s too radical.”

Joe and Jill Biden campaign in Des Moines, Iowa, on Feb. 3.

Democrats and Democratic-leaning voters share similar attitudes on a wide range of values and some specific issues, but there’s a difference of intensity. For example, most Democrats support making tuition free at public universities and building a government-run health insurance program. Backers of Sanders and Warren feel most strongly about those proposals, according to a survey in January by the Pew Research Center.

At the start of the year, Biden had the advantage among conservative and moderate Democrats. Liberal Democrats were divided among multiple candidates. Very liberal Democrats narrowly preferred Sanders over Warren, Pew surveys show.

But Biden and Warren failed to win much support when voting began.

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Exit polls in New Hampshire show Sanders won 46% of “very liberal” voters. He and Buttigieg competed heavily for “somewhat liberal” voters. Buttigieg and Klobuchar tied among moderates.

That left Sanders atop the field with 26% despite the fact that 53% of New Hampshire Democrats backed either Buttigieg, Klobuchar or Biden.

“It says a lot about the current Dem state of affairs that Bernie Sanders has a much better chance of winning the nomination after winning 26% of the vote in NH than he did after winning 60% of it four years ago,” tweeted David Wasserman, a political analyst at the nonpartisan Cook Political Report.

Democratic presidential candidate former South Bend, Ind. Mayor Pete Buttigieg speaks at a campaign event, Monday, Feb. 10, 2020, in Exeter, N.H.

Winning with a minority of the vote

Democrats face a somewhat similar situation to what Republicans went through in 2016 with their crowded field of candidates. Trump became the GOP nominee despite the fact that only 23% of Republican voters consistently supported him from the start of the nominating process through April 2016, according to Pew surveys.

Trump was helped by the fact that, unlike in the Democrats' nominating contest, many states awarded all delegates to the top vote-getter. Trump, for example, won all of South Carolina’s delegates despite getting less than a third of the primary vote.

In New Hampshire, Sanders and Buttigieg each won nine delegates despite Sanders’ 1.3-percentage-point victory over Buttigieg.

If Sanders gets a delegate lead, Democrats’ proportional allotment of delegates could make it difficult for others to catch him.

That could happen on Super Tuesday when one-third of delegates are at stake, according to Pfeiffer. If Sanders wins California by 8 to 10 percentage points, he could net 100 more delegates than others get. Overcoming such an advantage would require another candidate not just beating him in other states but doing so with a large majority.

If Warren, Biden, Klobuchar, Buttigieg and Bloomberg are all still competing on Super Tuesday, Sanders could effectively wrap up the nomination by April 1, Pfeiffer predicted.

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Democratic presidential candidate Sen. Amy Klobuchar, D-Minn., greets supporters outside a New Hampshire primary polling location, Tuesday, Feb. 11, 2020, in Manchester, N.H.

Attacking Sanders

Sanders has not been subject to a sustained attack. Warren hasn’t gone after him in their competition for the party’s most liberal voters.

Criticism from the center-left may increase, particularly over Sanders’ championing of "Medicare for All."

“Others say it’s Medicare for All or nothing,” Buttigieg says in a Nevada ad. “I approved this message to say, the choice should be yours.”

Nevada’s most politically powerful union, the casino workers’ Culinary Union, declined to endorse a candidate, but it warned members that the insurance they would get under Medicare for All might not be as good as their union-negotiated plans.

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Sanders narrowly lost Nevada to Hillary Clinton in 2016. He’s made extensive outreach to Latino voters since.

Sanders was crushed by Clinton in South Carolina, the first state with a significant African American population to vote.

His prospects are threatened by the possibility of a single candidate winning a large share of the black vote, according to analysts at the University of Virginia’s Center for Politics. That threat has greatly diminished as Biden struggles.

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Even before Iowa and New Hampshire failed to winnow the field of center-left candidates to one obvious challenger to Sanders, Democrat Mike Rosler worried about whether the party could overcome internal divisions.

“It’s the Democrats’ to lose as long as there’s no infighting,” Rosler, 44, a research scientist from Massachusetts, said at an event for Biden last month in New Hampshire. “If the vote is not splintered, it’s unwinnable for Trump and it’s unlosable for Democrats. I think it can only be self-defeated.”

Contributing: Joey Garrison

This article originally appeared on USA TODAY: Bernie Sanders' success in the 2020 primary worries some Democrats