Sen. Elizabeth Warren of Massachusetts found herself under fire from several of her opponents in the 4th Democratic presidential debate on Tuesday night, reflecting her steady rise to the top of the polls in recent months.

The debate was the first since Warren has surpassed Vice President Joe Biden in a number of early-state polls and effectively pulled even with him in some national surveys. Her new status as a front-runner was clear as soon as the conversation turned from impeaching President Trump — a topic on which the candidates broadly agreed — to healthcare.

When asked whether her proposed Medicare-for-All plan would require raising middle-class taxes, Warren said: “I have made clear what my principles are here and that is costs will go up for the wealthy and for big corporations and for hardworking middle class families costs will go down."

But Mayor Pete Buttigieg of South Bend, Indiana, who has advocated for a “Medicare for All Who Want It” alternative, criticized Warren for being evasive. “We heard it tonight. A yes or no question that didn’t get a yes or no answer,” Buttigieg said. “Your signature, senator, is to have a plan for everything. Except for this.”

“Let’s be clear, whenever someone hears the term ‘Medicare for All Who Want It,’ understand what that really means," Warren responded. “It’s ‘Medicare for All Who Can Afford It.’"

Buttigieg, who has tried to find an opening in the crowded primary field as a moderate alternative to Biden, shot back: ”I don’t understand why you believe the only way to deliver affordable coverage to everybody is to obliterate private plans, kicking 150 million Americans off of their insurance in four short years."

Warren has repeatedly dodged questions about whether her healthcare plan would result in a middle-class tax increase. Her focus on total “costs” for middle-class families instead of “taxes” was an attempt to thread that needle. But Sen. Bernie Sanders of Vermont, who has led the party leftward in recent years on single-payer healthcare, was more blunt.

“For virtually everybody, the tax increase they pay will be substantially less than what they were paying for premiums and out of pocket expenses,” Sanders said.

That led Sen. Amy Klobuchar of Minnesota, another moderate in the field, to join in the Warren pile-on.

“At least Bernie’s being honest here and saying how he’s gonna pay for this and that taxes are gonna go up," Klobuchar said. “And I’m sorry Elizabeth, but you have not said that, and I think we owe it to the American people to tell them where we’re going to send the invoice. The difference between a plan and a pipe dream is something you can actually get done."

The criticism of Warren continued when the discussion turned to her signature wealth tax.

“I think it’s part of the solution," former Rep. Beto O’Rourke of Texas said of Warren’s plan. But I think we need to be focused on lifting people up, and sometimes I think that Senator Warren is more focused on being punitive.”

“I’m really shocked than anyone thinks I’m punitive,” Warren said. "I don’t have a beef with billionaires.”

Warren finally got some cover from one her Senate colleagues, Cory Booker of New Jersey.

“You know, we’ve got one shot to make Donald Trump a one term president. And how we talk about each other in this debate actually really matters. I’ve had the privilege of working with or being friends with everybody on this stage. And tearing each other down because we have a different plan, to me, is unacceptable."

Later, Sen. Kamala Harris of California repeatedly pushed Warren to join her in calling for Trump to be banned from Twitter, on the grounds that he violates the platform’s terms of use by using his account for harassment.

“I don’t just want to push Donald Trump off Twitter, I want to push him out of the White House,” Warren responded.

Even Biden clashed with Warren. After he said he was the only one on stage with a record of significant political accomplishments, Warren mentioned her role in the creation of the Consumer Financial Protection Bureau. Biden turned to her and said in a raised voice, “I went on the floor and got you votes! I got votes for that bill! I convinced people to vote for it. So let’s get those things straight, too.”

Asked to respond, Warren said she was “deeply grateful to President Obama" and others who supported the creation of the agency.

“You did a hell of a job in your job,” Biden interjected.

“Thank you,” Warren said.