When President Donald Trump went to West Virginia this month to tout the Republican tax plan, his main political target in the state prodded the president on two major issues.

Sen. Joe Manchin, a Democrat running for re-election in a state Trump won easily in 2016, asked what would happen to West Virginia residents who choose not to get health care because of a provision in the GOP tax overhaul. He also questioned whether Republicans would cut funds from Social Security and Medicare to help offset projected budget deficits generated by tax cuts.

"I won't stop fighting to protect Medicare and Social Security for our seniors, the 200,000 West Virginians at risk of losing coverage, and to secure coal miner pensions," Manchin said in a statement earlier this month.

Health care and Social Security are always important issues for voters, and Democrats have often made them keystones of political campaigns. But with midterm congressional elections approaching, the issues have taken on more political importance for the party following Republican efforts to repeal the Affordable Care Act and GOP musings about shrinking social programs.

While Republican moves to overhaul Social Security, Medicare or Medicaid appear unlikely — at least for this year — Democrats are increasingly warning about the prospect because of the deficit concerns created by the tax plan. The GOP argues Democrats want to distract from the fact that they did not support the tax overhaul, the signature Republican achievement of Trump's first year in office.

Democrats' ability to sell voters on their vision for health care and warn about the possibility of cuts to Social Security and Medicare could prove crucial for candidates, such as Manchin, who are trying to win in red areas.

Democrats already heavily argued for protecting social programs in one key House election. Rep. Conor Lamb, D-Pa., won a March special election in a district Trump carried by 20 points. Former Vice President Joe Biden made campaign stops for Lamb and repeatedly argued the region's voters needed to elect Lamb to protect Social Security and Medicare.

"If we do nothing in terms of cutting programs, if we just keep things as they are, America's gonna go flat bankrupt over the next 10 years. Not a joke," Biden said at the time. "It's because this tax cut is not paid for. But they have a way to pay for it. And [Lamb is] gonna get in their way, they're afraid."

Biden, who has not ruled out running for president in 2020, is expected to campaign for House Democrats throughout the year and will likely make similar arguments.