Hillary Clinton took a shot at Bernie Sanders today when she released a proposal to provide 12 weeks of paid family and medical leave without raising taxes on households earning less than $250,000 per year.

Sanders is a co-sponsor of the FAMILY Act, which would provide for a similar amount of family and medical leave via a 0.4% payroll tax — $1.38 per week for a worker making median wages. Sanders’s campaign says that his own plan for paid family and medical leave would cost a similar $1.61 per week for the average worker.

Clinton’s proposal goes out of its way to argue that this is the wrong approach, since “middle class families deserve a raise, not a tax increase.” However, her proposal doesn’t specify how, exactly, the wealthiest two-ish percent of American households would pay for a benefit that is received on a worker-by-worker basis. The white paper declares that the policy will be paid for by “a combination of tax reforms impacting the most fortunate,” but there is no discussion of which taxes will be raised (or which tax expenditures will be eliminated) in order to match the benefits provided by the FAMILY Act.

That could have something to do with the fact that, as has been pointed out before, Clinton’s previous pledge to not raise taxes on the lower 98 percent of earners severely limits her ability to make the math work on a wide array of progressive economic policies. However, paid family and medical leave is a cheap enough program — again, it can be paid for by a 0.4% payroll tax — that it shouldn’t be all that hard to come up with equivalent savings in the tax code that would only affect families with household incomes over $250,000 per year.

This being the case, it’s hard to call Clinton’s proposal for paid family leave a “plan,” since there’s no roadmap as to how she gets from Point A (no family leave) to her stated goal of Point B (revenue-neutral family leave). Nor is there any present legislation on which she’s modeled her proposal — instead, she’s gone out of her way to repudiate legislation that a sizable subset of Democrats in Congress support.

All she’s done is say that paid family and medical leave are good, but that minuscule payroll tax increases are bad.

I mean really they are saying this is a "plan" when basically its just a press statement with no details pic.twitter.com/xWFSFoIQSX — Zaid Jilani (@ZaidJilani) January 8, 2016

Sanders, for his part, is not amused:

If President Johnson had taken the same position as @HillaryClinton that a small payroll tax was unacceptable we wouldn't have Medicare. — Bernie Sanders (@BernieSanders) January 8, 2016

After all, this is exactly the kind of debate that Sanders was hoping to have when he jumped in the race. Paid family leave has now been added to the list of issues on which Clinton has attacked Sanders from the right — a list that already included debt-free college and universal health care. However, each issue on that list brings to mind the more fundamental question of whether taxes are good if they pay for good things, or if they are only good if someone else is paying them.

That’s a question Sanders is fairly confident he has the better answer to: