NORTH LAS VEGAS, Nev. — Sen. Elizabeth Warren scrambled Thursday to take advantage of what her supporters — and even some rivals — saw as a highly effective debate performance, but faced continued questions about whether she has time to get her presidential campaign back into contention as her ideological soulmate, Sen. Bernie Sanders, tightens his grip on front-runner status.

Warren's campaign said it pulled in $2.8 million in donations in one day Wednesday — her largest one-day fundraising haul and even more than the $2.7 million Sanders campaign says it raised. That fired up supporters who had been disappointed by her fourth-place finish in the New Hampshire primary and her lackluster performance in the debate there.

"All I can say is we're just getting started," a pumped-up Warren said in North Las Vegas Thursday morning as her supporters chanted her signature slogan, "Persist! Persist!"

But it is late to be "getting started" in a race whose pace is quickening, at a time when many Democrats are questioning whether any candidate can slow or stop Sanders, I-Vt.,who is consolidating the support of progressive Democrats while center-left voters are splitting their votes among a number of candidates.

Warren of Massachusetts has been lagging in polls in the large swath of states — including California — that will vote over the next two weeks, appearing in fourth place in several states. Roughly 40% of all convention delegates will be allocated during that period.

"She had a very good performance, but the history of these debates is that they have not done much to change poll numbers," said Mark Mellman, a Democratic strategist who is not supporting a particular candidate but is heading a political action committee that has run anti-Sanders ads.

He cited the example of Sen. Kamala Harris of California who, early in her presidential campaign, got a big burst of donations and media attention after a pointed attack on Joe Biden's civil rights record. That buzz quickly faded, and Harris dropped out of the race in December.

As Warren enjoyed the cheers of energized supporters, former New York City Mayor Michael Bloomberg, who was widely seen as the chief loser in Wednesday night's debate, returned to his strong suit on Thursday — intimidating financial force. His campaign released spending figures ahead of a federal disclosure deadline showing that he had spent $409 million through the end of January and already had 2,400 people on his campaign staff.

"Mike is the only candidate with the record and resources to build the national infrastructure Democrats need to beat Donald Trump," campaign manager Kevin Sheekey said in a statement.

Wednesday's debate, which marked Bloomberg's first turn on the stage, drew record viewership, just short of 20 million people, according to Nielsen. Bloomberg's lackluster debut could cost him support from voters who are still taking the measure of a candidate who entered the race late and has been known to most Democrats only through the ubiquitous television and digital ads he has financed with his personal fortune.

Bloomberg proved to be the perfect foil for Warren, who has built her campaign around denouncing the undue political and economic influence of the wealthy.

Warren's supporters were delighted to see her returning to the fighting spirit that drove her rise to the top of many polls last summer and fall, before she fumbled the roll out of her healthcare policy. Her support in polls tumbled after that; Sanders — even after he suffered and recovered from a heart attack — was a big beneficiary.

She came in a disappointing third in the Iowa caucuses, and an embarrassing fourth in the New Hampshire primary.

To get back in the game in Wednesday's debate, Warren shelved her past reluctance to attack her rivals by name. She lacerated Bloomberg by portraying him as a sexist billionaire; gave withering critiques of her rivals for center-left voters, Sen. Amy Klobuchar of Minnesota and Pete Buttigieg, former mayor of South Bend, Ind.; and portrayed former Vice President Joe Biden as too cozy with Senate Majority Leader Mitch McConnell, R-Ky.

"Last night was amazing!" said Connie Piro, 62, a retired Mandalay Bay waitress at Warren's rally Thursday. "I was so happy the whole time. I was going, 'Yes! Yes! Yes! Yes!'"

Piro said she had been concerned that Warren was slipping in the polls, but believes her debate performance will reverse that trend.

"I think it really helped a lot, I really do," said Piro, one of about 150 people who packed into a small Warren field office before heading out to canvass for her.

"She demonstrated that she can stand up to these men and put them in their place where they belong."

Other supporters, concerned about Warren's slide, have formed a super PAC and have poured money into ads supporting her. The group, Persist PAC, has spent $795,724 in Nevada — more than any outside political group — according to Advertising Analytics, a company that tracks political ad buys.

Their activity runs counter to Warren's opposition to such outside-funding groups, and clashes with her marquee promise to finance her own campaign solely with grassroots donations. But in a sign of the financial pressures on her campaign, Warren has refused to renounce the group.

Asked about the shift of position, Warren said Thursday that she would not ask the group to stop its ads because she was not facing a fair fight with the many other candidates who are benefiting from Super-PAC support.

"All the men who were on the stage all had either super PACs or they were multibillionaires who could rummage around in their sock drawers and find enough money to be able to fund a campaign," she told reporters Thursday. "If all candidates want to get rid of super PACs, count me in — I'll lead the charge. But that's how it has to be. It can't be the case that a bunch of people keep them and only one or two don't."

Sanders criticized Warren for her change of position, though not by name: "You can't change a corrupt system by taking its money. I am proud to be the only non-billionaire in this race without a super PAC spending millions of dollars to support me."

Although Sanders argues that he does not have a super PAC in his corner, he has received significant backing from the super PAC affiliated with National Nurses United, which has spent hundreds of thousands on his behalf. Buttigieg has backing from the Vote Vets PAC. Biden has had a super PAC acting on his behalf since late last year, and backers of Klobuchar recently launched one as well.

By law super PACs can take unlimited donations, which campaigns cannot do. They can't coordinate directly with a campaign, but they are typically run by people with close ties to the candidate, as is the case with the Persist PAC.

The Warren campaign said the donations that poured directly into its coffers on Wednesday included $1 million that came in during the debate itself. By mid-afternoon Thursday, Warren said on Twitter, they had received $5 million from the moment she stepped onto the debate stage.

The candidate who got the lightest dose of criticism from Warren was Sanders, who is her biggest obstacle to winning the nomination. But even he, for the first time, came in for some contrasts.

"Democrats want to beat Donald Trump, but they are worried," Warren said. "They are worried about gambling on a revolution that won't bring along a majority of this country."

And she criticized his campaign for holding a narrow, exclusive view of Medicare for All.

"Bernie has a good start," she said. "But instead of expanding and bringing in more people to help, instead his campaign relentlessly attacks everyone who asks a question or tries to fill in details about how to actually make this work. "

But her more pointed focus of criticism on Buttigieg, Klobuchar, Biden and Bloomberg signaled a calculation that if Warren can grow her base, it is more likely to come from the center-left than from Sanders' hard core of loyal supporters.