Westerville, Ohio (CNN) Elizabeth Warren's campaign said on Wednesday that it is studying a range of options for paying for "Medicare for All," leaving open the possibility that the presidential candidate may ultimately diverge from Sen. Bernie Sanders on how his sweeping health care plan -- which Warren has endorsed -- would be paid for.

"She's reviewing the revenue options suggested by the 2016 Bernie campaign along with other revenue options. But she will only support pay-fors that meet the principles she has laid out in multiple debates," a Warren campaign aide said in a statement provided to CNN.

The campaign aide also said that the total cost of Medicare for All is unknown and that estimates vary by trillions of dollars. They did not provide details on what "other revenue options" the campaign is studying, and declined to comment on whether Warren may eventually put out her own details on paying for Medicare for All.

A new study by the Urban Institute , released Wednesday, said that federal spending on health care would increase by roughly $34 trillion under a single-payer plan similar to Medicare for All. That's in line with earlier studies that pegged the cost at around $32 trillion.

While Sanders has not detailed how he would raise the revenue needed to pay for Medicare for All, he included a variety of options when he released his 2016 campaign proposal and his updated bill in April. Among those listed in his most recent iteration are a 4% levy on employees, exempting the first $29,000 in income for a family of four. He also suggests imposing new taxes on employers, hiking the marginal tax rate on those making above $10 million, boosting the estate tax and establishing a wealth tax.

Warren's campaign statement comes on the heels of a contentious presidential debate Tuesday night in Ohio, where Warren was asked no less than half a dozen times on stage about whether Sanders' signature health care platform would raise taxes on the middle class and how she would like to pay for it.

Every time, the Massachusetts Democrat -- standing squarely center stage as a new front-runner in the 2020 Democratic race for President -- refused to state that taxes would, in fact, go up for some Americans under her colleague's plan. Instead, she stuck to a well-rehearsed response about how costs would go up for corporations and the wealthy and come down for middle class families. She pledged that as President, she would not sign a health care bill into law unless it lowered costs for average Americans.

Sanders has also stressed that while he would impose taxes on the middle class, they would see their overall costs go down because they would no longer have to pay premiums, deductibles or co-payments when they seek care.

Warren's repeated dodges on questions about whether Medicare for All would result in higher taxes are notably out of character for the senator, whose candidacy for the White House has gained steady political momentum in large part thanks to her abundance of policy plans and a knack for explaining and advocating for those ideas clearly out on the campaign trail.

Less than four months out from the Iowa caucuses, Warren's support for Medicare for All has stood out as a rarity. Even as she has unveiled policy plans at a rapid clip since launching her campaign on New Year's Eve, on the issue of health care, Warren has chosen to hold back from releasing a proposal of her own. Instead, she has stuck to publicly backing Sanders' Medicare for All -- a bill that she co-sponsored in the Senate -- and has not said that she will release a comprehensive health care plan of her own in the 2020 race.

"I'm with Bernie," Warren has previously said when asked about her vision on health care.

Tuesday's debate laid bare the political risks of Warren's backing of Sanders' Medicare for All, and foreshadowed that she is likely to continue confronting questions and criticism about tax hikes that could result from Sanders' proposal.

South Bend, Indiana, Mayor Pete Buttigieg summed up Warren's predicament this way: "Your signature, senator, is to have a plan for everything. Except this." Former Vice President Joe Biden accused Warren of being "vague."

Minnesota Sen. Klobuchar also joined the chorus, imploring her Senate colleague to acknowledge what Sanders himself had said earlier in the evening: "I do think it is appropriate to acknowledge that taxes will go up."

"At least Bernie is being honest here, saying how he's going to pay for this -- taxes are going to go up," Klobuchar said. "Sorry Elizabeth, you haven't said that. We owe it to the American people to tell them where we will send the invoice."

The grilling continued well after the debate ended. In an interview with CNN anchors and analysts later that spanned close to 20 minutes, Warren was again pressed multiple times to acknowledge that Sanders' Medicare for All plan would result in tax hikes for some American families. Once again, she stuck to her script.

"My commitment is: I will not sign a bill into law that raises costs on middle class families," Warren said.

There have been earlier signs that Warren and her campaign were leaving open wiggle room on Medicare for All.

At a town hall in Keene, New Hampshire, last month, Warren referred to Medicare for All as a "framework," saying: "Right now, what we've got in Medicare for All is a framework and it doesn't have the details."

The senator's senior adviser on the campaign, Joe Rospars , echoed that sentiment in a recent podcast interview, saying that some significant details have yet to be filled in on Sanders' Medicare for All plan.

"The question of the pay-for is: There's still a lot of details still to be filled in, in terms of both Bernie's bill that's out there but also the other versions of it, other candidates have their specific plans," Rospars said.

A veteran of Barack Obama's presidential campaigns, Rospars also said that he believes it's the "overall cost" of Medicare for All that most voters are focused on.

"I think there's a kind of disingenuousness to the — well, let's talk about taxes part of it," he said.