President Trump's decision to cut off Obamacare payments to insurers has driven up the number of zero-cost plans being sold to customers for 2018.

If Republicans use their tax bill to repeal the individual mandate, more insurers could end up fleeing the Affordable Care Act exchanges amid climbing financial losses, according to the American Academy of Actuaries.

Health-care issues are at the top of Congress’s hefty December to-do list. Republicans spent much of the year on a failed bid to repeal and replace ObamaCare. That’s left several programs and taxes hanging in the balance as the year draws to a close, in addition to the latest health-care drama thrust into the GOP tax-reform debate.

 The pace slowed in the third week of enrollment for 2018 Obamacare individual insurance as nearly 800,000 people signed up through the federal government website HealthCare.gov, down about 75,000 people from the previous week, a U.S. government agency reported on Wednesday.

The Senate Republican plan to use tax legislation to repeal the federal requirement that Americans have health coverage threatens to derail insurance markets in conservative, rural swaths of the country, according to a Los Angeles Times data analysis.

Health insurers fear they will be on the hook for greater healthcare costs if the CMS finalizes its proposal to allow states to define their own essential health benefits starting in 2019.