The recent debate between Democrats and Republicans on “Medicare-for-All” reveals just how fruitless our politics have become.

Medicare-for-All is Senator Bernie Sanders’s idea, which many Democrats have adopted as their next big health-care idea. (Other Democrats embrace less expansive ideas, like a more limited Medicare buy-in plan or a public option on the exchanges.) The plan, the cost of which Sanders pegs at $1.3 trillion a year (another study puts it at over $3 trillion), projects covering millions of still-uninsured or underinsured Americans in a Medicare-like government program.

Democrats sense an opening: As has often been the case, Democrats are strongest when comparing their “something” on health care to the Republicans’ “nothing.” But Republicans have learned that, so their strategy on Medicare-for-All will be the same as it was on Clintoncare and Obamacare: Make the Democrats’ something worse than the Republicans’ nothing.

This week we saw a coordinated Republican effort, led by President Trump and House Speaker Paul D. Ryan, to redefine Medicare-for-All as a Democratic effort to undermine Medicare, as they claim that the Sanders proposal will ruin Medicare as we know it. (Who knew Republicans cared about Medicare so much?)

There is a lot not to like about this latest turn in the health-care debate, but what is most troubling is what’s missing from it: any discussion of fiscal reality.

Forget a massive new expansion of the Medicare program. How is the nation going to pay for the one we already have? Here’s reality: Our nation’s deficit, plumped by Republican tax cuts, is now more than $1 trillion a year. Under current policy, the deficit is projected to rise further to over $2 trillion annually in 10 years.  The national debt, an accumulation of all those unpaid deficits, is projected to rise from its current $20 trillion to more than $35 trillion, or from 72 percent of gross domestic product to 109 percent, a percentage unprecedented in our history, even during the Second World War.

These numbers mean that not only will it be grossly irresponsible to add new spending proposals without large tax increases or spending cuts, but that the nation will continue to have to borrow simply to cover its existing and growing obligations, particularly for Medicare and Medicaid.

This fiscal gloom and doom is not new, but it should be given new urgency because of one very disturbing development: rising interest rates. For almost 10 years, the federal government, like most borrowers, has enjoyed almost “free money,” as interest rates approached zero.

But now, fueled by a growing economy and growing deficits, interest rates are on the rise again, meaning that payments to sustain the national debt will on their own become a major factor in increasing the debt. This vicious circle will, in turn, make it even harder for the government to meet its current obligations and force it to borrow even more, at ever higher rates, as it will need ever more enticement to find buyers for its debt.

If Democrats and Republicans don’t address the national debt — and soon — we won’t be debating Medicare-for-all, we will be left with Medicare for no one.

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