DETROIT (CBSDFW.COM/AP) — A high-profile clash pitting pragmatism against ideological purity dominated the early moments of the second round of presidential debates on Tuesday as moderate Democrats warned voters against nominating liberal candidates who embrace “wish-list economics.”

Working people “can’t wait for a revolution,” said little-known Montana Gov. Steve Bullock in a clear swipe at Vermont Sen. Bernie Sanders, a self-described democratic socialist who stood at center stage. “Their problems are here and now.”

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Massachusetts Sen. Elizabeth Warren, a progressive firebrand, pushed back: “We’re not going to solve the urgent problems we face with small ideas and spinelessness.”

The fight for the political left is just one subplot as the first wave of 10 candidates meets in Detroit. A second group of 10 that features early front-runner Joe Biden as well as Kamala Harris convenes Wednesday night. The groupings were chosen by debate host CNN at random.

Democratic presidential candidates Marianne Williamson, (L-R), Rep. Tim Ryan (D-OH), Sen. Amy Klobuchar (D-MN), Indiana Mayor Pete Buttigieg, Sen. Bernie Sanders (I-VT), Sen. Elizabeth Warren (D-MA), former Texas congressman Beto O’Rourke, former Colorado governor John Hickenlooper, former Maryland congressman John Delaney, and Montana Gov. Steve Bullock take the stage at the beginning of the Democratic Presidential Debate at the Fox Theatre July 30, 2019 in Detroit, Michigan. (Photo by Scott Olson/Getty Images)

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.

Former Texas Rep. Beto O’Rourke, who is participating in the first debate, is likely to qualify, even as he tries to stop his sharp slide in the polls.

Democratic presidential candidate former Texas congressman Beto O’Rourke speaks as Sen. Elizabeth Warren (D-MA) (L) and former Colorado governor John Hickenlooper listen during the Democratic Presidential Debate at the Fox Theatre July 30, 2019 in Detroit, Michigan. (Photo by Justin Sullivan/Getty Images)

Regarding immigration, O’Rourke said he opposes decriminalizing the act of crossing the border illegally.  He said he would free Dreamers from the threat of deportation and allow families and children to seek asylum.

But those especially at risk among Tuesday’s lineup include Bullock and former Colorado Gov. John Hickenlooper, the only governors in the running, and Midwestern natives such as Minnesota Sen. Amy Klobuchar and Ohio Rep. Tim Ryan. Also on stage: former Maryland Rep. John Delaney and author and activist Marianne Williamson.

The better-known contenders such as Warren, Sanders and South Bend, Indiana, Mayor Pete Buttigieg face a less dire challenge: to stand strong but avoid any major gaffes in a marathon campaign season against President Donald Trump that has only just begun.

It was the candidates with the most to lose who were most aggressive with their fellow Democrats in the early going Tuesday night.

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“We have a choice: We can go down the road that Sen. Sanders and Sen Warren want to take us, which is with bad policies like “Medicare for All,” free everything and impossible promises,” Delaney said. “It will turn off independent voters and get Trump reelected.”

Warren and Sanders promised to pursue bold liberal priorities if elected.

The high-profile New England senators are known for their unapologetic embrace of aggressive plans to overhaul health care, higher education, child care and the economy — ambitious and expensive steps that may be popular among many Democrats but give Trump and his Republican allies ample opportunity to cast all Democrats as extreme.

“We’re not going to solve the urgent problems we face with small ideas and spinelessness,” Warren charged, calling for “a Democratic Party of big structural change.”

The tug-of-war over the future of the party will decide exactly what kind of candidate Democrats put up against Trump in November 2020. It is a high-stakes debate that pits voters’ hearts against their heads as they weigh their desire for an aggressive response to Trump with finding a safe choice who’s best positioned to win.

It is a debate that is only beginning in many respects.

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

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.”

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)

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