MIAMI — It was Elizabeth Warren’s stage before she even stepped on it, and she took full advantage. During the first debate of the 2020 Democratic primary, the Massachusetts senator set the ideological bar for other progressives to clear.

The only top-tier candidate in Wednesday night’s lineup, Warren polls higher than any of those competitors -- higher, in fact, than all nine of them combined. Naturally, she got the first question.

The economy is doing well, Warren was asked, so why risk American prosperity by restructuring it?

“So, I think of it this way: Who is this economy really working for? It’s doing great for a thinner and thinner slice at the top,” she answered before condemning corporations that make pharmaceuticals, run private prisons, and drill for oil.

“When you've got a government, when you've got an economy that does great for those with money and isn't doing great for everyone else, that is corruption, pure and simple. We need to call it out. We need to attack it head on. And we need to make structural change in our government, in our economy, and in our country.”

It was a rap that voters in Iowa gymnasiums and New Hampshire coffee shops and South Carolina diners had already heard. For the rest of the country, it was a prime-time introduction to the anti-corporate progressivism that Warren has been perfecting at Harvard, in the U.S. Senate, and on the presidential campaign trail.

She delivered that answer, and most of her other answers throughout the night, without hesitation or interruption. While Warren trails former Vice President Joe Biden and Vermont Sen. Bernie Sanders, she didn’t have to fight either for the spotlight. Those two don’t take the stage until Thursday night, giving the two-term lawmaker an opportunity to focus on her policies without the distraction of their personalities.

Moderators asked her questions and then asked her competitors to respond to her answers. Aside from the sister of Hawaii Rep. Tulsi Gabbard, who tweeted angrily from that campaign’s account that “it’s clear who MSNBC wants to be president,” most of the candidates seemed to accept that Wednesday night belonged to Warren.

She was left to her own devices, and that will be to the delight of Republicans if she wins the nomination.

When NBC’s Lester Holt asked who on the debate stage would eliminate private insurance and establish a government-run plan in its place, Warren’s hand shot up automatically. Only New York City Mayor Bill de Blasio joined her.

“I'm with Bernie on ‘Medicare for All.’ And let me tell you why,” Warren declared in her first full endorsement of the idea. The problem with private coverage, she explained, returning to her anti-corporate theme, is the insurance and pharmaceutical companies that “try to bring in as many dollars as they can in premiums and to pay out as few dollars as possible for your health care.”

Higher premiums and rising copays are the result, she said. Anyone who disagreed, including some of those to the left and right of her, lacked courage: “There are a lot of politicians who say, ‘Oh, it's just not possible, we just can't do it, have a lot of political reasons for this.’ What they're really telling you is they just won't fight for it.”

Warren won applause for that answer from the progressive faithful assembled in the Miami arts center. She won’t be as lucky elsewhere when Republicans inevitably remind voters that, as a result, 180 million Americans will lose their private health insurance.

Former Rep. John Delaney previewed that attack when he asked why Democrats “have to stand for taking away something from people.”

The moderator moved on, and Warren didn’t bother with a rebuttal. At other times, the senator and her purple jacket seemed to fade into the blue backdrop as the other nine candidates competed for oxygen during the two-hour debate.

While a question about immigration sparked a spirited exchange and various displays of Spanish proficiency, Warren didn’t get to answer. Earlier in the day, she had travelled to a shelter for unaccompanied immigrant children in Homestead, about an hour outside Miami. But her prepared remarks on the topic went undelivered as Julian Castro, the former secretary for Housing and Urban Development, went after O'Rourke, a former Senate candidate -- and fellow Texan -- for supporting policies that would “still criminalize a lot of these families.”

Warren didn’t seem interested in bickering with anyone on stage. She didn’t even bother to mention President Trump, focusing instead on her own policies.

For his part, Trump proclaimed himself unentertained by the policy-heavy debate. The president tweeted out a one-word review: “boring!” Even then, a source close to the president declared the Massachusetts progressive the victor, texting RealClearPolitics that “Elizabeth Warren is winning the NIT tonight” -- a reference to the college basketball teams not chosen to participate in the NCAA’s “March Madness” tournament.

All the same, supporters, including Adam Green of the Progressive Change Campaign Committee, were thrilled with the candidate’s performance in what some have dubbed “the junior varsity debate.” Green’s organization has been spearheading a #SwitchToWarren initiative, not to draw votes away from Sanders but to sap the strength of the current front-runner. “The two honeypots for Elizabeth Warren in terms of new supporters,” he told RCP ahead of the debate, “are Biden-voters and undecided-voters because both of those pools are electability voters.”

Biden will make his case Thursday, but in many ways, the stage has already been shifted ever farther left before he steps onto it. The former vice president will share the spotlight with Bernie Sanders – the third member of the top-running triumvirate – while competing for the nomination of a party that has evolved past, and even eclipsed, the policies of his old running mate, Barack Obama.

Biden and Warren are sure to cross paths during one of the other 11 scheduled debates. Without interference from either of her top competitors, though, Warren was able to solidify her standing. She detailed her policies and, after disappearing in the melee for a bit during the second half of the debate, closed the night on a personal note.

“I am in this fight because I believe that we can make our government, we can make our economy, we can make our country work not just for those at the top. We can make it work for everyone,” she said.

“And I promise you this: I will fight for you as hard as I fight for my own family.”