Oklahoma Governor Mary Fallin has vetoed a bill that would make abortion a criminal offence in the US state.
Although she opposes abortion, she said the measure was vague and would not withstand a legal challenge.
The state senate on Thursday backed the bill that would have punished doctors who terminate a pregnancy with up to three years in prison. They would also be barred from practicing medicine.
To override the veto, lawmakers require a two-thirds majority in each chamber.
Abortion is legal in the US, and abortion rights activists have already described the bill as unconstitutional.
Two abortion clinics remain open in Oklahoma after the state recently enacted a number of new regulations affecting the facilities.