If the 2024 presidential election ever gets around to serious issues, you’re likely to hear a lot of happy talk from Kamala Harris and Donald Trump. The Democratic and Republican presidential nominees have a lot of plans for tax cuts and government giveaways, customized to please each candidate’s desired constituencies.

Both candidates, however, are whistling past America’s biggest economic challenge: A gargantuan national debt that is going to hamstring the flexibility of future presidents like never before. In the worst outcome, a debt crisis could trigger a nasty recession and years of punishing fiscal austerity that will drive voters to new levels of vexation.

The national debt recently hit a new record high of $35 trillion , and it’s only going to keep growing. Debt scolds have been warning about unsustainable levels of US debt for 30 years , and many predictions of a debt crisis haven’t come to pass.

But the United States is now in unprecedented territory for any government, ever, and financial markets have begun flinching at all the debt the US Treasury is issuing. Some analysts think the debt crisis has already begun .

In a recent episode of the Yahoo Finance Capitol Gains podcast above — see the 13:30 mark — debt expert Brian Riedl of the Manhattan Institute summarized what the nation needs to do to get the debt under control and forestall a crisis. Riedl recently wrote a 43-page report on the problem, which Yahoo Finance explained in a July 9 story .

The good news is that the United States doesn’t need to pay off the entire national debt — far from it. If we can stabilize the debt at current levels, which means sharply reducing annual deficits, it would put the nation on much sounder footing and probably be sustainable indefinitely, barring dramatic unforeseen developments such as a large war.

While the total national debt is $35 trillion, about $7 trillion of that is special securities held by the government in accounts such as the Social Security and Medicare trust funds. The amount that matters to markets is federal debt held by the public, which is all securities sold to investors by the Treasury Dept. That totals about $28 trillion , which is roughly the size of the US economy. So, federal debt held by the public equals about 100% of GDP.

The goal is to keep debt levels no higher than 100% of GDP. Alas, that’s not going to happen unless there’s dramatic change. Social Security and Medicare are both paying out more than they’re taking in, and that will only get worse as more Americans enter those programs. Net interest payments are rising sharply because interest rates have risen and the total amount of debt the government is financing has risen too. Other portions of the federal budget are simply underfunded.

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The Congressional Budget Office sees publicly held federal debt rising from 100% of GDP now to 122% within 10 years and only going up from there. The CBO doesn’t forecast recessions, so that doesn’t include any chance of a downturn during the next decade that would require fiscal stimulus, which always adds to deficits and makes the federal debt even bigger.

In Riedl’s analysis, closing the federal revenue-spending gap will require about $10 trillion of savings during the next decade. That could come in the form of budget cuts or new taxes, or a combination of both. But the scale of such an effort needs to be massive. Trimming a few programs or instituting new taxes on their own won’t come close to solving the problem.

What would solve the problem are changes to Social Security and Medicare cutting benefits for wealthier enrollees and raising the eligibility age. Medicare would have to be restructured to become more efficient. All that could be done while safeguarding benefits for lower-income seniors, who rely most on these safety net programs. Any such changes would doubtless be unpopular, yet far better than what would happen if the programs ran short of money and the only options were to cut benefits across the board.

Neither presidential candidate, needless to say, is campaigning on the vote-losing promise of cutting retiree benefits for some in order to sustain some benefits for all. More than that, each candidate is proposing tax cuts and deficit-funded policies that will make the whole problem worse, not better.

The biggest budget battle looming during the next two years is what to do about the 2017 Trump tax cuts for individuals, which expire at the end of 2025. Trump and his fellow Republicans want to keep all the 2017 tax cuts in place, while perhaps cutting the business tax a bit from its current 21% level. Trump also wants to eliminate taxes on income derived from tips and get rid of income taxes on Social Security benefits. All told, that would add about $6 trillion to the national debt .

Harris, like President Joe Biden when he was the Democrats’ 2024 presidential candidate, wants to let the 2017 tax cuts expire for those earning more than $400,000 but keep them in place for everybody else. Democrats also want to eliminate the cap on state and local tax deductions, which was part of the 2017 tax law, while also boosting tax credits for working parents and lower-income households. Her plan would add about $5 trillion to the national debt .

Both candidates, in other words, are going the wrong direction, if stabilizing the debt is the priority. “The reality is, 10 trillion is hard enough,” Riedl told Yahoo Finance on the Capitol Gains podcast. “Harris and Trump are probably going to push it up to 15 or 16 trillion right away.”

Both candidates, meanwhile, say they’ll protect Social Security and Medicare, with no changes to benefits. That “makes it mathematically impossible to stabilize the debt,” Rield says.

In Washington, D.C., everybody knows what it will take to finally do something to get the debt under control: a crisis that makes it apparent to everybody that something needs to be done and there’s no other choice. That’s the least competent and most expensive way to deal with the problem — but voters themselves probably wouldn’t have it any other way.

No politician can get elected by vowing to reform retiree programs — remember when President George W. Bush tried to reform Social Security back in the day? That's especially true now that mass disinformation allows cranks and scaremongers to transmogrify any reasonable-sounding plan into Armageddon.

Many voters say they’re worried about the imposing size of the national debt, but most people want somebody else to pay to fix it. The inevitable result is that we’ll all end up paying, and it will be a lot more than necessary.

Rick Newman is a senior columnist for Yahoo Finance . Follow him on X at @rickjnewman .

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