A top aide for Bernie Sanders isn't saying exactly how his boss plans on paying for health care, opting for the vague explanation of "progressively."

Yet, not disclosing the exact figures breaks a campaign pledge, as CNN pointed out:

Bernie Sanders could break his pledge to release details on how he would pay for his health care plan before the Iowa caucuses…

His campaign released details Wednesday of how Sanders will pay his $1 trillion dollar infrastructure plan and his $75-billion-a-year plan to make public college and universities tuition-free. But noticeably absent was his plan to pay for Medicare for all, a price tag that some estimates put at $15 trillion.

CNN remembers the promise Sanders made on its program State of the Union earlier this month to release those details before February 1.

But according to campaign manager Jeff Weaver, that's not going to happen:

I don't have a date for that. Not necessarily before the caucuses.

All he would say is that Sanders' Medicare-for-all plan will be paid "progressively," similarly to his previous health plans.

What is a more likely explanation, as Legal Insurrection notes, is that Sanders is holding off on the specifics before the caucuses so that would-be voters don't get turned off by the realization that it will probably come directly from their pockets. But then again, his staunch supporters probably don't care.

Perhaps they will care once they realize something he did promise: imposing even more taxes on the middle class to fund his paid family leave proposals. After all, that's exactly what "progressively" means.