Though Republicans are itching to start on their promises to “repeal and replace” the Affordable Care Act, many of them worry about repercussions if the process stalls or takes too long.

The GOP will most likely have to take a piecemeal approach to rolling back the health care legislation, a process Senate Majority Leader Mitch McConnell has said will be the first priority of the 115th Congress.

A new health care law might not take effect for up to three years, The Associated Press reported, in order to give Congress and President-elect Donald Trump enough time to come up with a feasible replacement.