One of Donald Trump s best-known promises and quite possibly one of his most important, politically is his vow to preserve two of Americas most beloved government programs.

I am going to protect Social Security and Medicare, Trump said in his July speech at the Republican National Convention, repeating a line hed said many times before and would say many times afterwards.

But Trump didnt mention another vital program: Medicaid , which pays medical bills for roughly 1 in 5 Americans. This omission does not appear to be accidental.

When HuffPost asked the Trump campaign last month whether the Republican nominee would extend his no-cuts pledge to Medicaid, the campaign offered a vague, bland response.

As President Trump said, he will release more details but his overall position on healthcare remains the same: bring down costs and increase the quality of care by improving competition in the marketplace, national press secretary Karoline Leavitt said in a statement emailed to HuffPost.

That non-denial denial is just one of several reasons to think Trump and Republicans might in fact target Medicaid if they get the chance. And while its an open question whether they would be able to get major cuts all the way through Congress, the consequences would be substantial, for the federal budget and for the many millions of Americans who depend on the program.

It would be the type of policy stance that might matter to voters in a presidential election at least, if they knew about it.

Why Medicaid Matters To Both Parties

Medicaid had nearly 73 million enrollees as of June, a number that includes low-income children and working-age Americans, for whom the program covers nearly all medical bills. It also includes several million low-income seniors and people with disabilities who use Medicaid to pay for nursing homes, prescription drug copayments and other expenses that their Medicare policies do not.

Democrats and other champions of the program generally consider Medicaid a success not because they think its perfect, but because of the financial security, access to medicine and improvements in health it provides to a large group of economically vulnerable Americans. Among other things, the programs defenders note, a dramatic expansion of Medicaid through the Affordable Care Act is the primary reason Americas uninsured rate has reached record lows.

Republicans have a very different view of Medicaid. They see a bloated, inefficient program that they say yields few benefits and disincentivizes low-income people from working all at a massive, economy-distorting cost to the taxpayer. Medicaid is now one of the biggest single line items in the federal budget, with annual expenditures that exceed $500 billion. That doesnt even include the more than $200 billion contributed by states, which manage the program.