Liberals clash with moderates over Medicare for All, immigration and race in 2nd Democratic debate

The first heat of the Democrats' second round of presidential primary debates in Detroit featured 10 candidates vying for the nomination, and the discussions became heated over issues and policies surrounding health care, race, immigration, the military and age.

Within minutes of starting their opening statements, the candidates emphasized the need to defeat President Donald Trump in the 2020 election.

Sens. Bernie Sanders and Elizabeth Warren were at center stage, giving voters on the party's left flank a chance to size up the two leading progressives in their first head-to-head match-up.

Warren and Sanders used their opening statements to hammer an economic and political system they say is rigged for the wealthy and corporations.

Sanders and Warren slapped back against their more cautious, moderate rivals who ridiculed Medicare for All.

"I don't understand why anybody goes to all the trouble of running for president of the United States just to talk about what we really can't do and shouldn't fight for," said Warren, a Massachusetts senator, decrying Democratic "spinelessness."

She defended single-payer health insurance and other "big ideas" as policy fights worth having. 

"I get a little bit tired of Democrats afraid of big ideas," Sanders said, agreeing with Warren. 

Sanders noted that half of U.S. households "are living paycheck to paycheck.“

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Sanders' plan to provide free universal health care, known as Medicare for All, has become a litmus test for liberal candidates, who have embraced the plan to transform the current system despite the political and practical risks. Medicare for All would abandon the private insurance market in favor of a taxpayer-funded system that would cover all Americans.

"Health care is a human right, not a privilege. I believe that. I will fight for that," Sanders said.

Meanwhile, several other candidates took veiled shots at the two leading progressives for liberal proposals, including single-payer health care.

Montana Gov. Steve Bullock knocked "wish-list economics," saying that working people "can't wait for a revolution." Bullock got his first debate opportunity on stage after failing to qualify for the June events.

Former Colorado Gov. John Hickenlooper said Democrats can solve problems without "expansion" of government. He added that with Sanders' liberal policies Democrats "might as well FedEx the election to Donald Trump."

But Sanders pushed back, noting that polling shows him beating Trump in a clutch of key Midwestern states. He said he would beat Trump because the president is "a fraud and a phony.“

Also on stage was former Maryland Rep. John Delaney, who said Warren and Sanders' health care proposals are "dead on arrival" because they would essentially outlaw private health insurance.

Mayor Pete Buttigieg called on his party to stop the infighting.

"It is time to stop worrying about what the Republicans will say," Buttigieg declared. "It's true that if we embrace a far-left agenda, they're going to say we're a bunch of crazy socialists. 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. So let's just stand up for the right policy, go out there and defend it."

Sanders was also asked during Tuesday's debate what differentiates his aversion to the global U.S. military presence from Trump's opposition to being "policemen of the world." Sanders responded that Trump is "a pathological liar.“

Sanders said he'd work as president to strengthen the United States' standing with the United Nations and focus on diplomacy, not military action.

Buttigieg pledged to withdraw from Afghanistan — where he served — by the end of his first year in the White House.

The mayor of South Bend, Indiana, also advocated for a three-year sunset provision for authorizations of the use of military force, noting that those deployed to Afghanistan will soon be too young to have been alive during the Sept. 11 attacks.

On the issue of race, Buttigieg said that as mayor of the diverse town of South Bend “the racial divide lives within me.” 

Buttigieg, who is white, says he didn't become mayor "to end racism," but he had worked on issues of race, crime and poverty affecting communities of color.

He has been criticized for his handling of an officer-involved shooting that took him off the campaign trail last month. He came home to a black community that was frustrated and outraged nearly five years after the Black Lives Matter movement was born amid increased awareness about the shootings of unarmed black men by police.

Pointing to water problems in communities like Flint, Michigan, author and activist Marianne Williamson said poor minority areas fall victim to a "collectivized hatred" that only deepens their problems.

Hickenlooper said Democrats must show they can "delegate an urban agenda" for substantive changes in schools and affordable housing.

Asked how she would combat white supremacy, Warren said she would call it out as "domestic terrorism," blaming Trump for racially unequal policies in economics and education.

Tuesday's debate is the first since Trump used racist language to attack four Democratic congresswomen of color, calling on them to "go back" to their countries even though all four are U.S. citizens.

Former Texas Rep. Beto O'Rourke stood by his refusal to call for decriminalizing crossing the U.S.-Mexico border by undocumented migrants, saying he will instead overhaul immigration policy enough that "I expect people who come here to follow our laws.“

O'Rourke said that if he is elected president, he will protect those seeking U.S. asylum and people brought to the country illegally as children.

Other presidential candidates called for full decriminalization. Warren said current laws have given Trump "the power to break families apart" at the border.

Sanders said he doesn't consider women and children who walked thousands of miles criminals, adding that Trump has demonized all immigrants.

But Bullock said decriminalization may "play into Donald Trump's hands.“

The issue of age also turned up toward the end of the debate. 

Buttigieg is the youngest candidate in the Democratic field at age 37. But he turned a discussion of age at Tuesday's debate into an attack on congressional Republicans for continuing to support Trump.

Sanders is the oldest candidate on the debate stage. But the 77-year-old Vermont senator said Democratic voters must look for a candidate with "vision."

Standing next to Sanders, Buttigieg repeated his call for a "new generation" of Democratic leaders.

In the June debates, Warren was matched up against several trailing candidates, with Sanders and the other leading candidates debating on the second night.

The first votes in the Democratic primary won't be cast for six more months, yet there is an increasing sense of urgency for many candidates who are fighting for survival. 

More than a dozen could be blocked from the next round of debates altogether — and effectively pushed out of the race — if they fail to reach new polling and fundraising thresholds implemented by the Democratic National Committee.

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O'Rourke, who participated in the first debate, is likely to qualify, even as he tries to stop his sharp slide in the polls. But those especially at risk among Tuesday's lineup include Bullock and Hickenlooper, the only governors in the running, and Midwestern natives such as Minnesota Sen. Amy Klobuchar and Ohio Rep. Tim Ryan. 

Klobuchar, who is working to keep her campaign alive, aligned herself with the pragmatic wing, saying, "We are more worried about winning an argument than winning an election.“

Former Vice President Joe Biden and California Sen. Kamala Harris headline debate Wednesday night's debate, also featuring 10 candidates. 

The 76-year-old Democrat is expected to face new questions regarding his past policies and statements about women and minorities — both key constituencies he needs to claim the Democratic Party's nomination and ultimately defeat Trump.

CNN, the debate host, chose the groupings at random.

The ultimate nominee won't be secured until the party's national convention next July in Wisconsin.

The Associated Press contributed to this report.