DETROIT (Reuters) - Elizabeth Warren and Bernie Sanders offered an unabashed defense of their progressive policies during a Democratic presidential debate on Tuesday, as their more moderate rivals criticized their proposals as unrealistic and politically untenable.

The debate frequently pitted the two U.S. senators against the other eight candidates on stage, with healthcare and immigration policy highlighting the divisions between the two camps.

On the first night of back-to-back debates, Democrats were united in stressing the urgency of defeating Republican President Donald Trump in the November 2020 election. But they delivered bruising critiques of their party rivals’ positions as detailed policy disagreements dominated the nearly three-hour event.

The dispute between the moderate and liberal wings of the Democratic Party highlighted the central question of the nominating contest: Which candidate in the field of more than two dozen would be best positioned to beat Trump next year?

The moderate wing, led at times by Montana Governor Steve Bullock, argued Democrats risk losing voters after moving too far to the left in the opening debate last month in Miami.

“Watching that last debate, folks seemed more concerned about scoring points or outdoing each other with wish-list economics than making sure Americans know we hear their voices and will help their lives,” said Bullock, who emerged as a forceful voice in his first presidential debate.

In contrast, progressives argued their policies would excite voters and allow them to draw a distinct contrast to Trump.

Warren rebuked former U.S. Representative John Delaney, who often played the role of foil to the progressives during the debate, firing back at his criticism of her policies.

“I don’t understand why anybody goes to all the trouble of running for president of the United States to talk about what we really can’t do and shouldn’t fight for,” she said.

Sanders also bristled at arguments that his proposals could not be realistically achieved, saying: “I get a little bit tired of Democrats afraid of big ideas. Republicans are not afraid of big ideas.”

Trump has been eager to paint the entire Democratic field as socialists, seeking to make any eventual nominee unsavory for voters by arguing Democrats want to raise taxes, open the U.S. borders and take away private healthcare.

Trump’s campaign spokeswoman echoed that sentiment in a statement about the debate on Tuesday night, calling the field “radical Democrats” with a “socialist message.”

Pete Buttigieg, the mayor of South Bend, Indiana, encouraged his party to ignore Trump’s inevitable criticism.

“If we embrace a far-left agenda, they’re going to say we’re a bunch of crazy socialists,” he said. “If we embrace a conservative agenda, you know what they’re going to do? They’re going to say we’re a bunch of crazy socialists.”

HEALTHCARE, IMMIGRATION

As the front-runners in polls among the candidates debating on Tuesday, Sanders and Warren vowed not to attack each other, but needed to distinguish themselves in their bid to gain ground on the leader in the race, former Vice President Joe Biden.

Instead, they often found themselves teaming up to defend policy positions they share instead of drawing contrasts.

The first section of the debate centered on a dispute about the future of the U.S. healthcare system, and whether Democrats should embrace Medicare for All proposals that would have the government take over the health insurance industry.

Democrats have made access to affordable healthcare one of their defining issues as the Trump administration has worked to chip away at former Democratic President Barack Obama’s signature 2010 Affordable Care Act.

Delaney attacked the Medicare for All proposal that has been put forward by Warren and Sanders, arguing Americans who like private insurance should be able to keep it.

“Why do we have to be the party of taking something away from people?” said Delaney.

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He pointed to Warren and Sanders: “They are running on telling half the country that your health insurance is illegal.”

Warren interjected to defend a government takeover of health insurance.

“We’re not trying to take healthcare away from anyone. That’s what Republicans are trying to do,” she said.

Sanders, who has introduced a Medicare for All bill in the U.S. Senate, said: “Healthcare is a human right, not a privilege. I believe that, I will fight for that.”

The candidates also differed on immigration policy - disagreeing on whether illegal border crossings should be decriminalized.

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“You don’t have to decriminalize everything,” Bullock said. “What you have to do is to have a president in there with the judgment and the decency to treat someone that comes to the border like one of our own.”

Warren disagreed, saying: “We need to expand legal immigration, we need to create a path for citizenship not just for dreamers but for grandmas and for people who have been working here in the farms and for students who have overstayed their visas.”

“You are playing into Donald Trump’s hands,” Bullock said.

CRITICAL CUTOFF

Among the lower-tier candidates who were aiming to produce a race-changing moment, Tuesday night’s debate may have been the final performance for some.

Several were hoping to replicate the performance of U.S. Senator Kamala Harris, who enjoyed a brief surge after a strong performance in the first debate after confronting Biden on the issue of race.

But no standout moments emerged from the debate.

Candidates like U.S. Representative Tim Ryan and former Colorado Governor John Hickenlooper remain at risk of failing to qualify for the third debate in September in Houston.

The Democratic National Committee will double its fundraising and polling requirements to qualify for participation in the next debates in September and October.

Eight candidates have so qualified for the next round of debates: Biden, Warren, Sanders, Harris, Buttigieg, U.S. Senator Cory Booker, former congressman Beto O’Rourke and entrepreneur Andrew Yang, according to their campaigns.

Ten more candidates will face off on Wednesday night, including Biden and Harris.