President Donald Trump has an Obamacare problem. His administration restarted its efforts to kill the health care law this week, backing a lawsuit that argues all of the Affordable Care Act is unconstitutional. Now, Trump faces a question that has confounded Republicans in recent years: if courts toss out Obamacare, how do you replace it with an alternative that expands coverage, cuts costs and keeps the law’s most popular parts in place? The White House has no easy answers. When the GOP tried several times to repeal Obamacare in 2017, voters overwhelmingly disapproved of the plans. Americans grew to like the existing law more when they saw projections that the Republicans’ alternatives would leaves tens of millions more people uninsured or increase costs. Democrats flipped 40 House seats and control of the chamber in last year’s midterms in large part by criticizing the Republican push to repeal the ACA. After the drubbing, Republican leaders in Congress have had little appetite for reopening the Obamacare fight, instead focusing on several top Democratic presidential candidates’ calls for a government-run “Medicare-for-all” health care system. Then Trump jumped into the fray in recent days. Focusing on health care ahead of a pivotal 2020 election, in which Republicans will try to defend the White House and a Senate majority and retake House seats, carries massive political risk. There’s little evidence to suggest voters trust Trump and the GOP to come up with a health care plan if the president gets his wish and the Supreme Court scraps Obamacare. “The one lasting effect of the repeal and replace debate is that the ACA is actually more popular than ever. That will make it harder to talk about repealing and replacing it,” said Larry Levitt, senior vice president for health reform at the Kaiser Family Foundation. “The repeal and replace debate in 2017 did the one thing that seemed impossible: which was to make the ACA popular.” Trump calls GOP the ‘party of health care’ Since his administration backed the lawsuit to scrap Obamacare on Monday, Trump has talked about vague plans to come up with a superior health-care law. On Friday, he said his administration would come up with “a plan that is way better than Obamacare.” “We’re always going to take care of people with pre-existing conditions,” Trump told reporters in Florida, referring to perhaps the most popular piece of Obamacare, which the administration-backed lawsuit would end. “I said it before, the Republican Party is going to be the party of health care.” After 2017, voters may not want the GOP in charge of health care. While the Republican plans to repeal Obamacare took various forms, all of them fared poorly in public opinion polls. The GOP passed one form of health care overhaul in the House, then came one vote shy of approving a different version in the Senate. Trump has repeatedly attacked GOP Sen. John McCain, even after his death last year, for helping to stop Republicans from scrapping the ACA.