Donald Trump’s proposal for maternity leave is less a genuine transformation of Republican policy than a plan with limited benefits and no real funding. PHOTOGRAPH BY EVAN VUCCI / AP

Earlier this week, Donald J. Trump, a man who once said that pregnancy is “an inconvenience for a business,” announced in Aston, Pennsylvania, that those in leadership should “put themselves in the shoes of . . . the mom struggling to afford child care.” In Nixon-and-China fashion, Trump seemed to nudge the Republican Party past its deepest fears by establishing paid maternity leave as something the government should guarantee and actually pay for.

While Trump’s tax-deduction-centered child-care offering fits into a long history of G.O.P. tax-cut proposals, Trump’s maternity leave combines two horribles from the Party’s point of view: a business mandate and an entitlement program that pays people not to work.

When you look at the details, however, Trump’s proposal is less a genuine transformation than a plan with limited benefits and no real funding. The Trump program would essentially give women unemployment insurance for six weeks of maternity leave. Most women are already guaranteed as much as twelve weeks of unpaid leave through the Family and Medical Leave Act, so for employers this is a much smaller burden then you might think. The payments generally come out to roughly half of the employees’ pay, to a maximum that ranges from $235 a week in Mississippi to $698 a week in Massachusetts. In other words, the total benefit, distributed over six weeks, is no more than $1,410 to $4,188. If you live in a Republican-leaning state, the number is likely to be at the lower end of the range. In Florida, a swing state that has gutted its unemployment-insurance system, the maximum would come out to $1,650, before taxes.

Trump estimates the total national cost of his proposed maternity benefits (there is no paternity benefit) at $2.5 billion. This is probably a little low, but not absurdly out of line. Trump says that paying this will require no new funds, just wringing fraud out of a system that the Trump campaign says made $5.6 billion a year in improper payments.

There are two difficulties with this math. The first one is that there is not close to enough fraud in the system to pay for Trump’s plan. The government’s audit estimates about $3.2 billion in overpayments in 2015 (you can download very detailed data here), of which about $900 million was paid back. It’s not clear where Trump’s number comes from; it is close to the overpayment numbers for earlier years, when extended unemployment benefits were still in force. Most of those improper payments come from mistakes (often by employers) or lapses in documentation, not from double-dipping by people who collect benefits while working. Based on U.S audit estimates, about $850 million, out of a total of $32 billion in payments, comes from fraud—a meaningful number, but less than the Trump campaign claims. Still, for the sake of argument, let’s say we could eliminate every single dollar’s worth of unemployment-insurance mistakes. That gets close to Trump’s $2.5 billion cost.

The bigger difficulty, though, is that whatever these numbers, the Trump plan is based on a misrepresentation of how the current unemployment-insurance program works. The money paid into the program isn’t the federal government’s to give out. The federal government usually collects only forty-two dollars per employee in unemployment taxes. All the rest of the money used for unemployment—including all the money currently getting paid out in benefits—is collected by states, through state-payroll taxes.

“It’s all state money,” Wayne Vroman, an economist with the Urban Institute, a nonpartisan think tank, told me.* “The money that the federal government collects is used only for administration and extended benefits, which are no longer in force.” The federal government did pay to extend unemployment benefits for as long as seventy-eight weeks after the financial crisis, but that program expired at the end of 2013. Dipping into state money to pay for leave is something that the states don’t want to do, and couldn’t do even if they did want to. “The money that the states get in unemployment-insurance taxes goes into trust funds that by law can’t be used for any purpose but to pay unemployment benefits,” Vroman explained.

So, really, what Trump promised on Tuesday night is a program with minimal benefits that would have to be paid for by the states. If you happen to live in California, New York, or states that might be willing to raise their payroll taxes to pay maternity leave through the infrastructure of the unemployment program, it might not be a bad idea. But that’s a far cry from a genuine federal paid maternity leave. It’s also a nonstarter in Republican-leaning states (and woe to those mothers invited to confront the unemployment-insurance bureaucracy). Vroman said that, when presented with a plan to extend unemployment to cover family leave, under Bill Clinton, not a single state legislature wanted to sign on.

If you’ve got this far, you will probably be wondering about a similar bottom-line comparison of Hillary Clinton’s health-care plan. So here it is: her plan calls for a new program that would offer parental leave lasting for twelve weeks, based on two-thirds of the employee’s pay. The median weekly earnings of a woman aged twenty-five to thirty-four were $679 in 2014; the Clinton plan would cover two-thirds of that, or about $452, for twelve weeks. That comes out to an average of $5,424. The benefit could also be used by fathers (though probably not by both parents for one child). This is essentially three times the benefit that Trump’s plan estimates. Clinton is clear about how she would pay for it: a tax increase. It probably wouldn’t have to be a big one. A family-leave plan with similar benefits introduced in Congress last year envisions an increase in payroll taxes of two-tenths of one per cent of wages, or about $1.60 a week for the typical full-time worker. Passing a tax increase is by no means easy street, but it’s how real benefits get paid for.

The choice is between a plan that provides a significant, though probably not transformative, benefit paid for with higher taxes, and a second plan whose funding is a fiction, and which relies on misrepresenting how the tax system works. Still, each candidate now has a plan and can talk about it in the upcoming debates.

Should Trump win the election, the maternity plan will likely be discreetly tucked away in a deep file drawer. But if he loses Trump has already done the most intransigent wing of his party a useful service. There is no better way to kill a big idea than to push a smaller, dumber version.

*_An earlier version of this sentence misidentified Wayne Vroman's affiliation. _