DES MOINES, Iowa (AP) — The Republican-controlled Iowa Senate has begun debate on a bill that would ban most abortions in the state after 20 weeks of pregnancy.

The chamber launched floor discussion Tuesday night. It’s unclear when lawmakers will vote on the measure, though it’s expected to pass. It still requires legislative activity in the GOP-led House.

Iowa law bans abortions at the end of the second trimester of pregnancy, or 27 weeks. The bill would ban most abortions after 20 weeks of pregnancy, based on the disputed premise that a fetus can feel pain at that stage.

There would be exemptions where the mother’s life is at risk. A woman can terminate a pregnancy between 20 and 24 weeks if the fetus has a fatal condition.

More than 15 states have passed similar legislation, and a handful faced legal challenges.