There are limits to that process, but Republicans’ myriad efforts to repeal the Affordable Care Act provide a guide. The bill, which ultimately failed, would have turned Medicaid, the health care program for the poor, into block grants to the states while slowly rolling back its expansion under the Affordable Care Act and squeezing overall spending on the program.

“Last year when we were taking a run at repealing Obamacare, there was a very serious effort to reform Medicaid,” said Senator Patrick J. Toomey, Republican of Pennsylvania. “We got close to uniting Republican senators on the idea that not only do we need to change the architecture of the program but also long-term growth of the program.”

This would be their easiest play, especially if the Republican majority expands in the Senate.

“If Republicans keep the House, I have no doubt they will redouble their efforts to repeal the Affordable Care Act and slash funding,” said Representative Frank Pallone Jr. of New Jersey, the highest-ranking Democrat on the Energy and Commerce Committee, which oversees the program, in an email. Indeed, if Republicans keep control of Congress, they might view this as a mandate from voters.

Social Security is probably, but not entirely, secure

Republicans have long toyed with the notion of allowing some private investments in Social Security, but there has been no serious legislative attempt since President George W. Bush was smacked down when he tried to change the program in 2005.

President Barack Obama offered some cuts in Social Security in exchange for new revenues in the “grand bargain” he pursued with the House speaker at the time, John Boehner, toward the end of both of their terms. But House Republicans rejected that notion, and it collapsed under the weight of partisan brawls.

Further, the retirement program is generally considered less of a threat to fiscal solvency than Medicare since its outlays are not expanding as fast as the health programs.

[Read more about campaign pledges regarding Social Security.]

And given the political polarization, Democrats and Republicans are unlikely to agree on a plan to overhaul the program, which would be necessary for any major changes.