Bernie Sanders fought Hillary Clinton to a draw in the Iowa caucus, but he’s crushing her in the bidding war to increase federal spending, promising tens of trillions of dollars in new government expenditures over the next decade.

In consequence, though the sensible sexagenarian secretary of state may be succeeding with the seniors, the septuagenarian socialist senator is simply smashing it with the 17-to-30 set.

What’s not for them to love? Bernie is proposing to make college free, nationalize health insurance, increase Social Security payments, spend more to subsidize private pensions, and sundry other things.

Clinton, who claims not to be a socialist, but who cannot explain the difference between “progressive Democrats” and socialists, seems not to oppose any of these ideas in principle. She just thinks we can’t arrive at Sanders’ socialist utopia quite as quickly as he supposes.

What both Sanders and Clinton have totally ignored is that we haven’t even figured out to pay for the welfare state we have, let alone how to pay for a massively expanded one.

At the end of January, our total national debt stood at just over $19 trillion dollars, up more than $7 trillion during the Obama administration and another $5 trillion or so during the George W. Bush administration.

More than $5 trillion of the total debt is owed by government to itself, most of it in the form of IOUs put into the Social Security Trust Fund and other government retirement funds, but the amount owed by the public also now stands at a record amount: more than $13 trillion.

To put those numbers in perspective, consider this: the total value of all the goods and services produced in the U.S. economy in 2015 (what economists call the gross domestic product) was a bit shy of $18 trillion.

So, right now, our government’s total debt is greater than the value of everything that can be produced in a year by everybody in the country. The publicly held debt is “only” about three-quarters of that.

Economists debate whether the money owed by the government to itself should really count as part of the national debt, or whether we as citizens should worry about it. The argument for not worrying about it is simple: the government retirement funds that hold the debt can just decide that they don’t want to collect what they’ve been promised — and voilà, $5 trillion or so of debt disappears.

On the other hand, cancelling the intragovernmental debt wouldn’t change the fact that we’re going to need that money (and more!) to pay for the Social Security and other retirement benefits that we’ve promised to pay out in the future. Either the taxpayers are going to come up with all that money, or those benefits will be cut. So even if you don’t want to call it “debt,” citizens should definitely still worry about it.

But, for the most part, the government doesn’t worry about the intra-governmental debt. So, for example, in its recent report, the non-partisan Congressional Budget Office (CBO) focuses on the $13 trillion figure.

But even using that smaller number, we are in deep trouble.

Don’t take my word for it: that’s what the CBO says.

First, they note that this level of debt is historically large: the only time we owed so much, relative to GDP, was during World War II and its immediate aftermath.

Going deeply in debt to save the world from fascist totalitarianism made sense. What lasting achievement has the Obama administration accomplished with all the money it borrowed? Or the Bush administration, for that matter? Unsuccessful foreign policies and lackluster domestic growth, plus increasing partisan polarization and distrust of government generally.

Second, the CBO projects that, on current trends, the debt will just keep on getting bigger.

The government is structurally living beyond its means: subsidizing the voters of today, by borrowing from the taxpayers of tomorrow.

Third, the CBO observes that, because government debt decreases the amount of capital able to support the growth of businesses, we can expect our workers to be less productive and wages to be lower in the future than they would be, if our government lived within its means.

Finally, our historically high levels of debt mean that we run the risk of not being able to borrow money if another crisis hits. And our unsusainable public finances today make another crisis more likely.

Joseph R. Reisert is associate professor of American constitutional law and chairman of the department of government at Colby College in Waterville.