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In the latest volley of her multi-front January offensive against Bernie Sanders, Hillary Clinton is zeroing in on his single-payer health care plan.

The Clinton campaign launched an all-out assault on Wednesday, flooding cable television with surrogates to attack Sanders for not releasing details of his plan. The Clinton campaign also held a conference call with reporters to ramp up the pressure on how the proposal would raise taxes.

After landing blows against Sanders on guns and electability, Clinton’s attack from the right on health care seems odd, at least on its face. Fully 81% of Democrats favor a Medicare-for-all plan, like the one Sanders is proposing, according to last month’s Kaiser Health poll.

But like so much in politics, Clinton’s fight is not what it seems. It’s not really about about health care, but about taxes and effectiveness — with a bank shot at Sanders’ electability.

Meanwhile, Sanders has responded by trying to move the debate back to the more favorable terrain of health care. He accused Clinton of adopting "Karl Rove tactics," as spokesperson Michael Briggs put it, to oppose universal health care, and flip-flopping on the issue to boot.

Who wins this fight, if there is even a clear winner, will largely be determined on who wins the framing of it.

Team Clinton’s argument, in a nutshell, is that Sanders is afraid to release details of his single-payer health care plan because it contains a massive tax hike on the middle class that would exacerbate economic inequality.

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Clinton has vowed not raise taxes on those who make less than $250,000 a year. Sanders, on the other hand, would need a "sweeping tax increase on the middle class" to fund his health care plan, Clinton spokesperson Brian Fallon said on the conference call Wednesday.

"What he’s promising right off the bat are tax increases that would adversely impact the take home pay," Fallon said.

Whether an argument on taxes convinces Democratic primary voters that Clinton cares more about economic inequality than Sanders remains to be seen, but she has a point on the missing details of his plan.

Sanders has been saying since at least July that he would roll out his Medicare-for-all plan “in the very near future,” but it has yet to come. In his capacity as a senator, he’s introduced legislation on the issue many times the past, but he has yet to explain how he would pay for it.

Sanders’ campaign released a fact sheet Wednesday explaining how the senator would pay for various programs, but a single-payer tax plan was not among them.

Asked Tuesday night on CNN if he still planned on releasing details of his plans before the Iowa caucuses on Feb. 1, Sanders replied, "Absolutely. If I said we’re going to do it, that’s what we’re going to do."

But his campaign manager, Jeff Weaver, confirmed Wednesday that the campaign may miss that deadline.

"The Clinton campaign, unfortunately, does not get to dictate when we put things out," Weaver told Chuck Todd on MSNBC’s "MTP Daily," saying it would come "when it’s ready."

And as Sanders noted, when Obama attacked Clinton for wanting to raise taxes through an individual mandate to pay for her health care plan, Clinton fired back hard.

"Since when do Democrats attack one another on universal health care?" she said in a video distributed by the Sanders campaign Wednesday. "This is wrong, and every Democrat should be outraged because this is the kind of attack that not only undermines core Democratic values, but gives aid and comfort to the very special interests and their allies in the Republican Party.”

There are plenty of good, progressive arguments Clinton could use against Sanders’ health care plan, but they’re not the ones team Clinton is emphasizing, at least for now.

If it comes down to whether Democratic primary voters care more about expanding health care or reducing taxes, the latter likely wins. Nearly one-in-five Democrats said health care was their top issue in a recent Washington Post/ABC News poll, compared to just 2 percent who said tax policy was most important.

But Clinton is also subtly evoking an electability argument against Sanders. By raising the issue of Sanders’ alleged tax hikes, team Clinton is reminding Democratic primary voters that Republicans will do the same, times infinity, if Sanders is the nominee. And while Clinton will probably never invoke the "S" word Republicans will have no qualms going after Sanders’ democratic socialism.

Still, for a candidate who has spent the entire campaign trying to convince voters she’s not a squishy moderate, attacking Sanders from the right on taxes may be a risky play.

"I’m not a political pundit, so I don’t know about the right versus the left," Sullivan said when asked about it by MSNBC on the call.

This article first appeared on MSNBC.com