South Bend Mayor Pete Buttigieg, Sen. Bernie Sanders, I-Vt., and Sen. Elizabeth Warren, D-Mass., participate in the first of two Democratic presidential primary debates hosted by CNN Tuesday, July 30, 2019, in the Fox Theatre in Detroit. (AP Photo…
South Bend Mayor Pete Buttigieg, Sen. Bernie Sanders, I-Vt., and Sen. Elizabeth Warren, D-Mass., participate in the first of two Democratic presidential primary debates hosted by CNN Tuesday, July 30, 2019, in the Fox Theatre in Detroit.

WASHINGTON - Story updated on July 31, at 12:18 am.

U.S. health care policies took center stage Tuesday night at the Democratic presidential candidates' debate, with more moderate challengers attacking Sens. Elizabeth Warren and Bernie Sanders, the leading progressives looking to oust President Donald Trump in the 2020 election.

Warren and Sanders have both called for a sweeping end to the country's current health care system centered on private company insurance plans offered to 150 million workers through their employers. But their views were under attack almost from the start of the debate on a theater stage in Detroit, Michigan, the country's auto industry hub.

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"We don't have to go around and be the party of subtraction and telling half the country who has private health insurance that their health insurance is illegal," former Maryland Congressman John Delaney said. "It's also bad policy. It'll under-fund the industry, many hospitals will close, and it's bad politics."

Often political allies

Warren, a former Harvard law professor, and Sanders, a self-described democratic socialist, are friends of long-standing and often political allies. They now are both looking for votes from the liberal wing of the Democratic Party. Both defended their position calling for a government-run health care system.

"This is not radical," Sanders of Vermont shouted at one point, noting that numerous other Western societies already have adopted government-run systems. "I get a little tired of Democrats who are afraid of big ideas."

Warren of Massachusetts rebuffed the critics, saying, "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." 

But their challengers lobbed multiple attacks at the pair, saying their proposals would, over four years or longer, upend the long-standing U.S. health care system, including government-subsidized insurance for moderate and low-income families under the Affordable Care Act, popularly known as Obamacare.

Sen. Amy Klobuchar of Minnesota, who has called for more incremental health care policy changes, said, "I have bold ideas, but they are grounded in reality."

Rep. Tim Ryan, D-Ohio, and Sen. Amy Klobuchar, D-Minn. talk during a break in the first of two Democratic presidential primary debates hosted by CNN Tuesday, July 30, 2019, in the Fox Theatre in Detroit.

Former Colorado Gov. John Hickenlooper said that Democrats had picked up 40 seats in the House of Representatives in the 2018 mid-term elections and not one of them had pushed for the Warren-Sanders Medicare for All plan.

"I'm a little more pragmatic," Hickenlooper declared.

'Recipe for disaster'

Ohio Congressman Tim Ryan called for a plan allowing Americans to buy into government-run insurance if they want to, but said that closing down the insurance industry "is a recipe for disaster," especially among union members who would face the loss of hard-won health care benefits through collective bargaining.

The moderate candidates also attacked Sanders and Warren on immigration issues, even as several candidates assailed Trump's immigration policies, including his since-abandoned practice of separating migrant children from their parents.

The moderate challengers criticized Sanders and Warren for proposing to end the filing of criminal charges against the thousands of undocumented migrants crossing the U.S.-Mexican border.

"We’ve got 100,000 people showing up at the border right now," said Montana Gov. Steve Bullock. "If we decriminalize entry, if we give free health care to everyone, we’ll have multiples of that." He said that by effectively encouraging migration to the United States, "You are playing into Donald Trump’s hands."

Ryan said, "If you want to come into the country, you should at least ring the doorbell."

Sanders answered that he does not think that immigrants should be prosecuted, saying, "If a mother and a child walk thousands of miles on a dangerous path, in my view, they are not criminals."

Warren called for civil penalties, not criminal charges against migrants arriving in the U.S. "The point is not about criminalization," she said. "That has given Donald Trump the tool to break families apart."

Throughout the night, the candidates sparred over foreign policy, Warren’s controversial plan for a wealth tax and debt-free college, payment of reparations to the U.S. descendants of slaves, trade, the city of Flint, Michigan's prolonged drinking water crisis, and even the age of the candidates. Buttigieg, who is 37, stood next to Sanders, who is 77, and was asked by CNN’s Don Lemon whether Sanders was too old to be president.

Buttigieg demurred, saying, "I don’t care how old you are, I care about your vision. ... We need the kind of vision that’s going to win. We can’t have the kind of vision that says, ‘Back to normal.'"

Sanders readily agreed with Buttigieg, boasting of the ideas he has advocated to dramatically alter the health care system and bring the pharmaceutical and insurance industries to heel. 

First of two nights

Tuesday's debate, lasting more than 2.5 hours, was the first of two nights with two groups of 10 Democratic candidates sparring with each other over domestic and foreign policy differences, but more importantly trying to make the case that they are the party's best hope to defeat Trump when he seeks re-election in 2020.

Trump's relentless attacks on Maryland Congressman Elijah Cummings, a prominent African American political leader, and the predominantly black city of Baltimore that he represents, drew sharp criticism from some of the Democratic presidential candidates.

"Donald Trump disgraces the office of the presidency every single day," Warren said. Klobuchar added: "I don't think anyone can justify what this president is doing."

The two debates are occurring six months ahead of the Democratic Party's first presidential nominating contests. The debates could prove pivotal in both winnowing the field, forcing the weakest challengers out of the race before the next debate in mid-September, and in solidifying the list of front-runners. It largely depends on who is perceived by pundits in the post-debate analyses as making a plausible case to be the Democratic standard-bearer, or, conversely, flubbing their opportunity on CNN's nationally televised broadcasts.

On Wednesday, former Vice President Joe Biden, currently the front-runner for the Democratic presidential nomination in national surveys of Democrats and some independents, will be at center stage. Some party stalwarts say he is the more moderate, center-left, politically safe choice to take on the unpredictable Trump, whose populist base of conservative voters remains strong.

Democratic presidential candidate former Vice President Joe Biden, speaks during the National Urban League Conference, Thursday, July 25, 2019, in Indianapolis.

Tuesday's debaters never mentioned Biden, even though all of them would eventually have to overtake him to win the Democratic nomination.

Biden had a shaky first debate performance a month ago, faltering as California Sen. Kamala Harris challenged him to explain his opposition three decades ago to forced busing of schoolchildren to racially desegregate public schools. Harris said that she, as a black woman and the daughter of an Indian mother and Jamaican father, benefited from such a busing program to attend a better school while growing up in California.

Biden, a fixture on the U.S. political scene for four decades, and Harris, a former state attorney general before winning election to the Senate, will be standing alongside each other on the debate stage. Biden is promising a more robust performance than in the first debate, saying, "I'm not going to be as polite this time." 

But questions remain about Biden's standing, whether at 76 he is too old to lead the country, even though Trump is 73, and whether Democratic voters want a candidate with more progressive views than Biden on health care, prevention of crime, migrant immigration at the U.S.-Mexican border and other issues.

Some analysts think Biden's top standing in national polls is at least partly a reflection of name recognition, from his 36 years as a U.S. senator, two unsuccessful runs for the presidency and two terms as vice president under former President Barack Obama.

Tough-on-crime legislation

On the same stage Wednesday, Biden is also likely to face a challenge from Sen. Cory Booker, an African American former mayor of Newark, New Jersey.

Booker has assailed Biden's support 25 years ago for get-tough-on-crime legislation that led to the disproportionate imprisonment of black defendants.

Biden recently offered a new criminal justice plan, reversing key provisions of the 1994 measure, such as ending the stricter sentencing for crack cocaine versus powder cocaine. Booker scoffed that Biden was hardly the best candidate to lay out a new criminal justice plan and has called for slashing mandatory minimum sentences.

Despite Biden's first debate stumbles, the ranks of the top Democratic candidates have changed little in national surveys.

Biden remains ahead of three challengers, all U.S. senators: Sanders, from the Northeastern state of Vermont; Warren, from neighboring Massachusetts, and Harris. Booker has edged up a bit in the polling, while South Bend, Indiana, Mayor Pete Buttigieg has slipped a notch. The remaining candidates are far down the ranks and struggling to gain a foothold.

A new Quinnipiac University national poll this week shows Biden leading the pack with 34% of Democrats and independents leaning Democratic, followed by Warren at 15%, Harris with 12% and Sanders with 11%.

Biden claims he has the best chance of making the Republican Trump the country's first single-term president in nearly three decades, denying him a second four years in the White House. 

National surveys, 15 months ahead of the Nov. 3, 2020, election, consistently show Biden winning a hypothetical match-up over Trump, whose voter approval ratings remain mired in the mid-40% range. Sanders often defeats Trump as well, although not by Biden's margin, while surveys show the other top Democrats potentially locked in tight, either-or outcomes with Trump.

Aside from Biden, Harris and Booker, the Wednesday debate stage also includes former Housing and Urban Development Secretary Julian Castro, Sen. Kirsten Gillibrand of New York, Congresswoman Tulsi Gabbard of Hawaii, Washington Gov. Jay Inslee, Colorado Sen. Michael Bennet, entrepreneur Andrew Yang and New York Mayor Bill de Blasio.

Five other Democratic candidates did not qualify for the Detroit debates, but the 20 who did had to have collected campaign donations from at least 65,000 individuals and hit a 1% threshold in at least three separate polls.

It gets tougher to appear on the stage at the third debate six weeks from now. To qualify then, candidates must have 130,000 campaign contributors and at least 2 percent support in four polls.

Only seven of this week's 20 debaters have already met the third debate criteria: Biden, Harris, Sanders, Warren, Buttigieg, Booker and former Texas Congressman Beto O'Rourke.