Detroit(CNN) The stark ideological divide within the Democratic Party was on full display during the second debate Tuesday night in Detroit, as the party's moderate candidates repeatedly tangled with front-runners Sens. Elizabeth Warren and Bernie Sanders, describing their ideas like "Medicare for All" and the Green New Deal as "fairytale" or "wish list" economics.
Standing at the center of the stage because of their leading position in the polls, Warren and Sanders took incoming fire from all sides during the first of two nights of debates in Detroit, but took on the fight with vigor and landed clean punches in response.
At the center of the back-and-forth was the question that has bedeviled the party since 2016: Will nominating a firebrand progressive from the far left energize enough voters to win back the White House? Or would doing so demolish Democratic hopes by alienating the centrist voters who cast ballots for Trump in 2016?
The debate got off to a fevered start as the 10 candidates on the stage debated Warren and Sanders' support for Medicare for All. Former congressman John Delaney of Maryland cited his father's union roots and his struggle to win health care, noting that many Americans who fought that same battle would resent Democratic efforts to completely restructure the health care system.
Rep. Tim Ryan of Ohio called Medicare for All "bad policy" and "bad politics." Montana Gov. Steve Bullock said Medicare for All would "rip away quality health care from individuals" and was an "example of wish-list economics."
"It used to be Republicans that wanted to repeal and replace, now many Democrats do as well," he charged.
Former Colorado Gov. John Hickenlooper warned that if Democrats want to "take private insurance away from 180 million Americans" -- a reference to the fact that Medicare for All would phase out private health insurance -- while guaranteeing that every American could get a government job through the Green New Deal, then "you might as well FedEx the election to Donald Trump."
"We have to focus on where Donald Trump is failing," Hickenlooper said. "Donald Trump is malpractice personified. We've got to point that out. ... Why are we lurching from one international crisis to another? All things he promised American voters. We have to focus on that and the economy and jobs and training, so that we can promise a future for America that everybody wants to invest in."
But Warren and Sanders, who formed a tacit alliance by bolstering one another's arguments while the others attacked them, relished the fight.
At one point, Warren effectively silenced Delaney by admonishing his dearth of policy ambition.
"I don't understand why anybody goes to all the trouble of running to the President of the United States to talk about what we really can't do and shouldn't fight for. I don't get it," Warren said in one of the most noteworthy moments of the debate.
Without shrinking away from her call for "big structural change," the Massachusetts senator acknowledged the fear that many Democrats feel. But she delivered a swift rebuke to her critics on stage, charging that the party could not choose caution and overlook the fervent desire for change.
"I get it. There is a lot at stake, and people are scared," Warren said. "But we can't choose a candidate we don't believe in just because we're too scared to do anything else. And we can't ask other people to vote for a candidate we don't believe in. Democrats win when we figure out what is right and we get out there and fight for it. I am not afraid and for Democrats to win, you can't be afraid either."
Sanders defended his legislative proposals in detail and argued that he could energize young voters, just as he did in 2016 before he lost the Democratic primary to Hillary Clinton.
"To win this election and to defeat Donald Trump -- which by the way, in my view is not going to be easy -- we need to have a campaign of energy and excitement and of vision," Sanders said. "We need to bring millions of young people into the political process in a way that we have never seen by among other things, making public colleges and universities tuition free and canceling student debt."
The ideological battle that played out over and over again at the Fox Theatre on Tuesday night was particularly salient here in Michigan, deep in the heart of the industrial Midwest, in a state that Trump was the first Republican to win since 1988.
Bullock, a late entrant to the race who did not qualify for the first debate, argued that his familiarity with red-state politics is a major asset in the campaign. He attempted to make the case that a message centered on the economy would help the party forge a pragmatic route back to the White House by reconnecting Democrats with the centrist, blue-collar voters who lean Democratic but cast ballots for Trump. But that did not appear to be the view of those in the crowd in Detroit, who delivered the most applause for Sanders and Warren.
Since Clinton's loss to Trump in 2016, Democrats have struggled with this internal debate about whether they must do more in 2020 to attract the centrist, white working-class voters who voted for Trump or if they can win the White House by embracing a bold, progressive agenda that would dramatically restructure government.
It is far from a settled question, and it has been complicated by the deep hunger within the Democratic Party to defeat Trump, particularly because of the rage over his racist comments and his xenophobia.
The debate played out first during a vigorous discussion of Medicare for All, which some of the moderates argued would be too costly and risky for the middle class.
"At the end of the day I won't support any plan that rips away quality health care from individuals," Bullock said. "This is an example of wish-list economics. It used to be Republicans that wanted to repeal and replace, now many Democrats do as well."
Author Marianne Williamson noted that she often agrees with Warren and Sanders on policy issues, but not on Medicare for All. "I'm normally way over there with Bernie and Elizabeth, but on this one. I hear the others," she said.
Williamson rejected Warren's argument that Democrats were using Republican talking points to demonize the Medicare for All plan. "I do have concern that it will be difficult. I have concern that it will make it harder to win, and I have a concern that it will make it harder to govern," she said.
There was a similar back-and-forth over the Green New Deal. Hickenlooper and Delaney argued that the Green New Deal was not a realistic plan to deal with the climate crisis. Hickenlooper argued that the "guarantee for a public job for everyone who wants one is a classic party of the problem" and "a distraction."
Warren, a co-sponsor of the Green New Deal, countered by saying that her policy agenda would create 1.2 million new jobs in green manufacturing and revitalize huge cities across this country.
"What you want to do is find the Republican talking point," she told Hickenlooper, "and say, oh, we don't really have to do anything. That's the problem we've got in Washington right now. It continues to be a Washington that works great for oil companies, just not for people worried about climate change."
Sanders, defending his plan to eliminate gas-powered car sales by 2040 under criticism from Ryan, replied that he gets "a little bit tired of Democrats (who are) afraid of big ideas."
"Republicans are not afraid of big ideas," the Vermont senator said. "They could give a trillion dollars in tax breaks to billionaires and profitable corporations. They can bail out the crooks on Wall Street. So please don't tell me that we cannot take on the fossil fuel industry, and nothing happens unless we do that."
He argued that the industry's investments are "destroying this planet."
"I say that is criminal activity," he said. "That cannot be allowed to continue."
"You don't have to yell," replied Ryan, whose state of Ohio has nearly 100,000 auto workers. "All I'm saying is we have to invent our way out of this thing. And if we're waiting for 2040 and a ban to come in on gasoline vehicles, we're screwed. So we better get busy now."
Another terse exchange between Sanders and Ryan unfolded as Sanders was questioned about the estimated 600,000 union members in Michigan who would be forced to give up their private health insurance plans if Medicare for All were enacted.
"Can you guarantee those union members that the benefits under Medicare for All will be as good as the benefits that their union reps fought hard to negotiate?" moderator Jake Tapper asked.
"They will be better because Medicare for All is comprehensive and covers all health care needs for senior citizens, it will finally include dental care, hearing aids and eyeglasses --," Sanders said.
"You don't know that, Bernie," Ryan interrupted. "You don't know that."
"I do know!" Sanders responded sharply. "I wrote the damn bill."
Ryan, undeterred, continued to make the point about union workers.
"Sen. Sanders does not know the union contracts in the United States," Ryan said. "I'm trying to explain that these union members are losing their jobs. Their wages have been stagnant. The world is crumbling around (them). The only thing they have is possibly really good health care, and the Democratic message is going to be -- we're going to go in, and the only thing you have left, we're going to take and do better. I do not think that's a recipe for success for us. It's bad policy and it's certainly bad politics."