President Donald Trump's promise to protect pre-existing conditions coverage, perhaps the most popular Affordable Care Act provision, rings hollow. That's because his administration is backing a lawsuit that would scrap it.

As Republicans face midterm election pressure from an energized Democratic base over their efforts to repeal Obamacare, the president tweeted Thursday that "all Republicans support people with pre-existing conditions" or "will after I speak to them" if they do not already. He added that "I am in total support."

Trump tweet

His administration's actions suggest otherwise. The Justice Department has declined to defend the health care law in court against a suit from 20 GOP-led states challenging Obamacare's constitutionality. They argue the rest of the law does not hold up after Republicans rolled back its individual mandate provision last year. By doing so, the Trump administration tacitly supported the suit, which could roll back Obamacare's coverage guarantees for people with pre-existing conditions if it succeeds.

As Democrats try to flip control of the House, candidates across the country have attacked the GOP for threatening coverage for people with pre-existing conditions. Amid the broadsides, Republican lawmakers who have pushed to repeal Obamacare for years are pledging to protect the provision. The GOP has good reason for its sudden shift on the issue: about three-quarters of Americans do not want pre-existing conditions protections to be reversed, according to a Kaiser Family Foundation survey earlier this year.