Westerville, Ohio (CNN) — Elizabeth Warren’s Campaign said Wednesday that it is exploring a range of options to pay for “Medicare for all,” leaving open the possibility that the presidential candidate could end up at odds with Sen. Bernie Sanders on how his sweeping health care plan – which Warren has endorsed – will be paid for.

“She’s looking at the revenue options offered by Bernie’s 2016 campaign along with other revenue options. But she will only support paying for anything that meets the principles she outlined in several debates, ” a Warren campaign aide said in a statement provided to CNN.

A campaign aide also said the total cost of Medicare for all is unknown, and that estimates range by trillions of dollars. They did not provide details on what” other revenue options ” the campaign is exploring, and declined to comment on whether Warren could end up putting out his own Medicare pay for all data.

A new Urban Institute study released Wednesday says Federal health spending will increase by about $ 34 trillion under a single-payer plan similar to Medicare for all. That’s according to earlier research that pegged the cost at about $ 32 trillion.

While Sanders did not detail how he would raise the revenue needed to pay for Medicare for all, he included various options when he released his 2016 campaign proposal and his updated bill in April. Among those listed in its latest iteration are the 4% employee tax, freeing up the first $ 29,000 in income for a family of four. He also proposes new taxes for employers, including a marginal tax rate on those making above $ 10 million, a property tax increase and the creation of a wealth tax.

Warren’s campaign announcement comes on the heels of Tuesday night’s contentious presidential debate in Ohio, where Warren was asked at least half a dozen times on stage about Sanders ‘ signature healthcare platform would raise taxes on the middle class and how she would like to pay for it.

Every time the Massachusetts Democrat, standing squarely in the spotlight as the new frontrunner in the democratic race for President in 2020, has refused to state that taxes would, in fact, go to some Americans under her colleague’s plan. Instead, she stuck to a well-rehearsed answer about how spending would go up for corporations and the wealthy and go down for middle-class families. She promised that, as President, she would not sign the health care bill unless it reduced costs for ordinary Americans.

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

Warren repeatedly dodged questions about whether Medicare for all would lead to higher taxes, particularly out of character for a Senator whose candidacy for the White house has received sustained political momentum thanks largely to her abundance of policy plans and ability to explain and promote these ideas explicitly on the campaign trail.

Less than four months out of the Iowa Caucuses, Warren’s support for Medicare for all stands out as a rarity. Even as she unveiled policy plans for a quick clip from the launch of her campaign on New year’s eve, on the health issue, Warren decided to refrain from releasing a proposal of her own. Instead, she stuck to public support for Medicare for all Sanders-a bill she co-sponsored in the Senate – and did not say she would release a comprehensive health plan of her own in the 2020 race.

“I’m with Bernie,” Warren previously said when asked about her vision for health care.

Tuesday’s debate exposed the political risks of Warren’s support for Medicare for all, and foreshadowed that she would likely continue to face questions and criticism about the tax increases 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. Besides. Former Vice President Joe Biden accused Warren of being “vague.”

Minnesota Sen. Klobuchar also joined the chorus, imploring his Senate colleague to acknowledge what Sanders himself said earlier in the evening: “I think it’s appropriate to recognize that taxes will go up.”

“At least Bernie is honest about how he’s going to pay for it – taxes are going to go up,” Klobuchar said. “Sorry Elizabeth, you didn’t say that. We in our multi-million dollar day in front of the American people said where we would send the invoice.”

The grilling continued after the debate. In an interview with CNN anchors and analysts later that spans about 20 minutes, Warren again pressed several times to admit that Sanders ‘ Medicare for all plan would lead to higher taxes for some American families. Once again, she sticks to her script.

“My commitment: I will not sign a bill into law that raises costs for middle-class families,” Warren said.

There were earlier signs that Warren and her campaigns were leaving the room open to sway on Medicare for all.

At a town hall in Keene, new Hampshire, last month, Warren called Medicare for all a “frame,” saying, ” right now, What we have in Medicare for All is a frame, and it doesn’t have the details.”

The Senator’s senior campaign adviser, Joe Rospars, echoed that sentiment in a recent podcast interview, saying that some important details still haven’t been filled in on Sanders ‘ Medicare for all plan.

“The issue of paying for it: There’s still a lot of detail still to be filled in, in terms of both Bernie’s bill that’s out there, but other versions of it, other candidates have their specific plans,” Rospars said.

A veteran of Barack Obama’s presidential campaigns, Rospars also said he believes it is the “total cost” of Medicare for all that most voters are focused on.

“I think there’s a kind of insincerity to the well, let’s talk about taxes part of it,” he said.