Energized by the successful passage of tax cuts, some Republicans are eying a new target: entitlement programs like Social Security and Medicare. House Speaker Paul Ryan is leading the charge, arguing that the only way to break the cycle of rising deficits and surging debt is to reduce entitlement spending.

Political resistance is likely to be fierce, not only because these programs are massively popular, but also because President Trump opposed any such cuts during his campaign. Even if the political hurdles can be cleared, though, the bigger problem is that this push for entitlement reform attacks the wrong target.

There is no wide-reaching entitlement funding crisis, no deep-rooted connection between runaway debts and the broad suite of pension and social welfare programs that usually get called entitlements. The problem is linked to entitlements, but it’s much narrower: If the U.S. budget collapses after hemorrhaging too much red ink, the main culprit will be rising health care costs.

Aside from health care, entitlement spending actually looks relatively manageable. Social Security will get a little more expensive over the next 30 years; welfare and anti-poverty programs will get a little cheaper. But costs for programs like Medicare and Medicaid are expected to climb from the merely unaffordable to truly catastrophic.

Part of that has to do with our aging population, but age isn’t the biggest issue. In a hypothetical world where the population of seniors citizens didn’t increase, entitlement-related health spending would still soar to unprecedented heights — thanks to the relentlessly accelerating cost of medical treatments for people of all ages.

What’s needed, then, is something far more focused than entitlement reform: an aggressive effort to slow the growth of per-person health care costs. Or — if that’s not possible — some way to ensure that the economy grows at least as fast as the cost of health care does.

Diagnosing the debt: It’s not about demographics

America’s long-term budget problem is very real. Already, the federal government has a pile of publicly held debts amounting to around $15 trillion, or about 75 percent of the country’s entire gross domestic product. That’s the highest level since the 1940s, yet the debt burden is expected to double by 2047 and reach 150 percent of the GDP, according to the Congressional Budget Office.

It makes sense to list entitlement spending among the culprits for the growing national debt, given that these programs have grown from costing less than 10 percent of the GDP in 2000 to a projected 18 percent in 2047. Part of this is simple demographics: As America ages, more of us become eligible for Social Security and Medicare, thus driving up expenses.

But there’s a crack in this demographic explanation: It only makes sense for the next 10 to 15 years. That’s the period of rapid transition when graying baby boomers will boost the population of seniors from around 50 million to more than 70 million. A change like that should indeed produce a surge in entitlement spending as those millions submit their enrollment forms.

By 2030, however, this wave will start to ebb, leaving the elderly share of the population at a roughly stable 20 to 21 percent all the way through 2060, based on the size of the population following the boomers and slower-moving forces like lengthening lifespans.

But think what this should mean for entitlement spending. As the population of seniors levels out in those later years, costs should naturally stabilize — at least, if demographics were really the driving factor.

This is exactly what you see for Social Security. The CBO expects total Social Security spending to leap up over the next decade but then settle at just over 6 percent of the GDP, at which point it will cease to be a major contributor to rising entitlement spending or growing debts. Social Security is thus a minor player in our long-term budget drama; if you cut the program to the bone, shrinking future payouts so that they won’t add a penny to the deficit, the federal debt would still reach 111 percent of the GDP in 2047.

Likewise, cuts to welfare and poverty-related entitlements like food stamps and unemployment insurance are unlikely to improve the debt forecast. In fact, spending on these entitlements has been dropping since the high-need years around the Great Recession and is expected to shrink further in the decades ahead — partly because payouts aren’t adjusted to keep up with economic growth, and partly because the birth rate has been falling and several programs are geared to families with children.

But the scale of the problem is totally different when you turn to health care. Spending on entitlement-related health programs — including Medicare, Medicaid and subsidies required by the Affordable Care Act — will never shrink or stabilize, according to projections. The CBO predicts these costs will grow over 65 percent between now and 2047 — and then go right on growing after that, heedless of the fact that the percentage of the population that’s over 65 should no longer be increasing.

Why is health care eating the budget? Per-person costs

Demographics aren’t responsible for the projected explosion in health care costs. More important than the growing number of elderly Americans is the growing cost per patient — the rising expense of treating each individual

The CBO found that the lion’s share — 60 percent — of the projected increase in health spending comes from costs that would continue to increase even if our population weren’t getting older.

The reasons for this are many, including the rising cost of prescription drugs and the fact that hospital mergers have reduced competition. But since 2000, per capita health costs in the U.S. have, on average, grown faster than the GDP. And while these costs rose more slowly after the Great Recession and the implementation of the Affordable Care Act, analysis from the Centers for Medicare and Medicaid Services suggests this slower growth rate won’t last.

Which is bad news for these programs, because if the problem were demographic, it’d be easier to solve. By mixing the kind of program cuts Republicans generally support with targeted tax increases favored by some Democrats, you could meet the short-term challenge posed by retiring baby boomers and raise enough money to cover the larger — but stabilizing — population of eligible seniors. But with ever-rising costs, there is no stable future to prepare for. To keep these programs funded, you’d need a wholly different approach — indeed a whole new perspective on mounting federal debt and the role of entitlements.

The future is a race between rising health care costs and economic growth, a race that the economy is losing. Each time health costs outpace the GDP, it creates what the CBO calls “excess cost growth,” which feeds the federal debt. If the government could close this gap, the long-term budget outlook would be a lot rosier.

There are two ways to solve this issue: Either contain health care costs — say through price regulation or more competitive markets — or boost economic growth enough to pay for this expensive health care. Success on either front would make health care spending look more manageable over future decades and lighten the debt load.

Entitlement reform needs health care reform to work

Few of the proposals that commonly fall under the heading of entitlement reform target the health care cost problem, which limits their ability to reduce the long-term debt.

Even when they do address health care, often the result is to shift — rather than solve — the problem. Say lawmakers decide to dramatically cut Medicare. That would indeed ease the government’s debt problem. But the underlying dynamic — the race between health costs and the GDP — wouldn’t really change. Seniors would still need health care, and per-person costs would likely still grow (maybe even faster, since Medicare is a relatively efficient program).

On top of all this, there’s also a deep-seated political barrier: It’s no good if one party picks its favored solution only to watch the other party dismantle it when they next take over. You need political consensus to make changes stick, and America is notably short on consensus right now.

In the end, though, it won’t do to just throw up our hands. Absent some workable solution, spending on health care will sink the federal budget, generating levels of debt that would hold back the economy and potentially spark a global crisis of confidence in the United States’ ability to borrow.

If Republicans are serious about addressing this challenge and reducing America’s debt, they need to find an approach to entitlement reform that can both reduce out-of-control health costs and also survive under Democratic governance.