ATLANTA — The top 10 Democratic candidates for president united around two ideas in a mostly civil two-hour debate Wednesday: President Trump must be defeated at the ballot box and they are each best positioned to do it.

Ideological divides remain, and policy differences persist. But they no longer serve as ends in themselves, as the real topic of debate has begun to shift with just 75 days before the Iowa caucuses.

The candidates in Atlanta focused instead on the unabated fear of Trump’s reelection, amid recent polling showing the president continues to have an edge in key Midwestern battleground states despite ongoing impeachment hearings.

Elizabeth Warren, Joe Biden, Bernie Sanders and seven other Democratic presidential candidates debated how to beat President Trump on Nov. 20 in Atlanta. (The Washington Post)

“You have to ask yourself up here, who is most likely to be able to win the nomination in the first place, to win the presidency in the first place?” Biden asked at the outset of the debate. “You have to win the presidency in the first place.”

Sen. Elizabeth Warren (D-Mass.) promoted her plan for a wealth tax as one of the “things that unite us.” Sen. Cory Booker (D-N.J.), who opposes such a tax, argued that the focus on taxation and not wealth creation would turn off voters. South Bend, Ind., Mayor Pete Buttigieg defended his lack of experience by citing his roots in the Midwest rather than in Washington. Sen. Bernie Sanders (I-Vt.) boasted that he had received more campaign contributions “than any candidate at this point in an election in American history.”

“I would argue we need something very different right now,” Buttigieg said. “In order to defeat this president, we need somebody who can go toe-to-toe, who actually comes from the kinds of communities that he’s been appealing to.”

Even attacks on other candidates came in the context of electability. Months after taking a blistering attack from Rep. Tulsi Gabbard (D-Hawaii) for her prosecutorial record, Sen. Kamala D. Harris (D-Calif.) got a chance to respond, and she opted to go after Gabbard’s potential in a general election.

“What we need on the stage in November is someone who has the ability to win,” Harris said.

Sen. Amy Klobuchar (D-Minn.), one of four female candidates still on the debate stage, argued that candidates should not be judged by physical characteristics but by their competency and smarts.

“If you think a woman can’t beat Donald Trump, Nancy Pelosi does it every single day,” Klobuchar said of the House speaker, who has become Trump’s chief antagonist.

The fifth Democratic debate came at an urgent time for many of the candidates who are struggling to stay in the mix. Since the first meeting in June, 22 candidates have appeared on the debate stage, seven of whom have since withdrawn and five more who have struggled to continue their campaigns without the spotlight of a party-sanctioned stage.

The nomination fight remains wide-open. With additional politicians still taking steps to join the race, and several on stage who might not make the cut for the next debate, nearly two-thirds of voters in New Hampshire and Iowa say they are still open to changing their minds.

After nearly a year of campaigning, the monthly debates have generally followed a familiar playbook, with the poorer-performing candidates turning on the front-runners and the front-runners struggling to maintain their position.

Wednesday’s debate, hosted by MSNBC and The Washington Post, was a more tame affair. Direct confrontations of Buttigieg, who has recently emerged as the polling leader in Iowa, were limited to attacks by Klobuchar and Gabbard on his limited experience. Warren escaped the criticism she attracted in October’s debate.

Biden continued to struggle in phrasing his answers, and he stumbled when he inaccurately said he had been endorsed by the “only” black woman elected to the U.S. Senate. Former senator Carol Moseley Braun of Illinois, the first black woman elected to that body, has endorsed him.

Former vice president Joe Biden falsely claimed he had the support of "the only African American woman that had ever been elected to the United States Senate." (The Washington Post)

Sanders, meanwhile, renewed his attacks on Biden for his vote to authorize the Iraq War in 2002. Biden challenged businessman Tom Steyer on his past investment in coal-fired power plants. Booker said Biden “may have been high” when he said recently that he did not want to legalize marijuana, since the position could turn off young and black voters.

But the fireworks of past meetings did not repeat themselves. Harris took a pass when offered a chance to repeat an attack she had leveled against Buttigieg for failing to connect with black voters. Instead, following the dominant strategy, she spoke about her own ability to beat Trump.

“We have to rebuild the Obama coalition to win,” Harris said. “I intend to win.”

Up to now, the candidates have pursued a policy contest on two parallel tracks. Liberal firebrands like Warren and Sanders, who are eager for a progressive populist uprising, have argued for big ideas with costs in the trillions that have no clear route for passing in Congress.

Biden, Buttigieg and Klobuchar have countered with a return to a more incremental path of progressive change sketched out previously by former presidents Bill Clinton and Barack Obama.

Those trying to paint themselves as bold change agents have had to paper over deep insecurity among Democratic strategists and voters about whether they can defeat Trump.

The recent Gallup numbers released this week showed only 36 percent of Democrats said they would prefer a candidate who aligns with them on most issues over one more likely to win.

Over the past several months, more-moderate candidates like Buttigieg and Biden have succeeded in turning the debate over Medicare-for-all into a proxy for a debate over electability.

“The fact is that right now the vast majority of Democrats do not support Medicare-for-all. It couldn’t pass the United States Senate right now with Democrats. It couldn’t pass the House,” Biden warned at the debate. “A hundred and sixty million people like their private insurance.”

While there is broad support for an expanded federal role in health care, the idea of replacing private health insurance is not a popular one, with support of just 37 percent of voters in a January Kaiser Family Foundation poll.

The 2018 midterm elections demonstrated that Democratic candidates who avoided the policy were more successful in competitive districts, many of them wealthy suburbs, according to an analysis by Alan Abramowitz, a political scientist at Emory University.

This concern had led several of the original co-sponsors of Sanders’s Medicare-for-all bill to reframe their support.

Harris, who entered the race boasting that she wanted to “eliminate” the hassles of private health insurance, has similarly pivoted to a plan that would heavily regulate the current industry without getting rid of it altogether.

Warren has more recently pivoted away from her full embrace of Sanders’s approach to Medicare-for-all, which foresees an attempt to start the country on the path to replacing most private health insurance as soon as he becomes president.

Buttigieg has gone through his own metamorphosis, after entering the campaign as an unknown hoping to brand himself as politically fearless.

He tweeted in 2018 that he favors “Medicare for All” and “any measure that would help get all Americans covered.” He made early headlines by embracing structural changes to the U.S. Supreme Court to weaken the conservative majority, and at the July debate he announced that Democrats should stop worrying about Republican attacks on their policies.

But as he rose into the top tier of candidates, he has pivoted to embrace more-moderate policies, and has gained traction in Iowa with an early advertising campaign that contrasts his plan to offer an optional Medicare program for all Americans.

That fear of alienating the American people and snatching defeat from the potential for victory hung heavy on the debate stage. Trump has yet to be offered a podium at the Democratic debates this year, but he has also never been absent from the proceedings.

“We cannot simply be consumed by Donald Trump, because if we are, you know what, we’re going to lose the election,” Sanders said.

A poll of Wisconsin voters released Wednesday by Marquette University Law School found Trump comfortably beating each of the four highest-polling Democratic candidates in a hypothetical matchup. Trump won the state over Democrat Hillary Clinton by less than a single percentage point in 2016.

“I want to talk about how we are going to win in 2020,” Steyer said at one point. No one on stage disagreed.