In his first address to Congress, President Trump lamented that “the past Administration has put on more new debt than nearly all other Presidents combined.” With federal debt approaching $20 trillion, he is right to be concerned about the rapid accumulation in recent years.

However, the president did not  mention of Medicare and Social Security, two of the largest and fastest-growing federal programs, and he has previously stated that he sees no reason to reduce spending on these programs. Treasury Secretary Mnuchin reiterated last week, “We are not touching [entitlements] now, so don’t expect to see that as part of this budget.”

Without substantive reform, it will be exceedingly difficult to address the country’s long-term fiscal problems, and it will only get harder if needed changes are delayed.

Medicare and Social Security already account for roughly two-fifths of all federal outlays, and they will account for a growing share of the federal budget over the coming decade. Medicare, Social Security, and net interest payments on the debt will account for roughly 55 percent of federal outlays by 2027, an increase over their already significant share of 45 percent last year.

Source: Congressional Budget Office, “10-Year Budget Projections, January 2017,” Tables 1-2 and 1-3.

Entitlement spending growth is a major reason that budget deficits are projected to surge over the next decade. Although forecasting ten years in advance is notoriously difficult, the deficit is estimated to exceed $1.4 trillion by 2027 and accelerate further after that, with trillions added to the debt as a result. By 2045, debt held by the public will almost double, to 145 percent of GDP according to the Congressional Budget Office. It is practically inconceivable that politicians would not step in before this happened.  However, if left unaddressed. debt at these levels would severely hamper economic growth, reduce living standards, and put increasing amounts of pressure on net interest payments and other areas of the federal budget.

Source: Congressional Budget Office, “Long Term Budget Projections, January 2017,” Supplemental Table 1. Annual Data Underlying Key Projections in CBO’s Extended Baseline.

Efforts to root out waste, fraud, and abuse, or to increase government’s efficiency are certainly worth pursuing, but proposals that eschew any kind of entitlement reform will leave the main drivers of debt in the long-term untouched.

Similarly, reducing regulatory barriers, improving the tax code, and generally developing a policy framework that allows the economy grow more rapidly are good ideas. To some extent, this could attenuate structural fiscal issues, but even higher rates of growth cannot make them go away.  According to one recent estimate, productivity growth would need to be twice projected levels just to stabilize the debt at slightly lower levels as a percent of GDP. Doubling productivity growth rates would be an impressive accomplishment, but there is a limit to how much it can help the country get out of its debt problem.

This is why entitlement reform is key. The unsustainable nature of these programs face mean that some reforms will have to be implemented: the only questions are when and what kind of changes will be made. The longer these reforms are put off, the inevitable changes will by necessity be larger and more abrupt.

For example, the Social Security Trustees estimate that an immediate and permanent benefit reduction of 16 percent for all beneficiaries would be enough to make the program solvent for the full 75-year projection. If nothing is done until the trust fund becomes insolvent in 2034, an immediate 21 percent reduction in benefits would be necessary.

Phasing in a gradual increase in the retirement age indexed to increases with longevity, or using the chained CPI for cost of living adjustments are measures that could go some way to making the program sustainable without sudden, significant benefits or tax increases. Kicking the can down the road will only increase the magnitude of eventual disruption, when changes will have to be concentrated in fewer years and the burden will fall on fewer people.

Part of the political difficulty stems from the public. People are wary of reforms that could affect their benefits, and they lack understanding regarding which programs are the drivers of the country’s debt. In a recent poll, 46 percent of respondents said they thought foreign aid, which accounts for roughly one percent of the federal budget, contributes “a great deal” to the national debt, a higher proportion than for any of the other programs polled. It is laudable to take a hard look at spending at all agencies and to excise inefficient or wasteful spending, this alone will not be enough to improve the overall fiscal picture.

Without real reform, the important task of placing entitlement programs back on a sustainable trajectory will be left for later generations—at which point the country will be farther down this unsustainable path.

Charles Hughes is a policy analyst at the Manhattan Institute. Follow him on twitter @CharlesHHughes.

This piece was originally published at Economics21.