Kansas' new governor vetoed a bill Monday that would require doctors and abortion clinics to tell their patients about a disputed treatment meant to stop a medication abortion.

The veto from Gov. Laura Kelly, a Democrat, sets up a showdown with a Republican-dominated legislature that appears to have the two-thirds majorities needed in both chambers to override the veto. Legislators are scheduled to return from a weeks-long break May 1.

The bill would require abortion clinics to display a sign notifying women that they could stop a medication abortion by taking the hormone progesterone -- even if they have already taken Mifepristone, the first of two drugs used in the procedure -- and doctors would have to tell a patient in writing that a medication abortion could be reversed. A clinic that failed to post a sign could be fined $10,000, and a doctor who failed to notify a patient could be charged with a misdemeanor for a first offense and a felony for a second.

Medication abortions using Mifepristone, also known as RU-486, are the most common way of terminating a pregnancy in Kansas, accounting for 61 percent of the total last year, according to statistics from the state health department.

Supporters of so-called "reversal" laws have cited a 2018 study led by Dr. George Delgado, a board member of the American Association of Pro-Life OB/GYNs and a voluntary associate clinical professor at the University of California, San Diego's medical school. They also noted that progesterone has been used for decades to prevent miscarriages.

Abortion-rights supporters have said the study was flawed and progesterone's use for reversing a medical abortion hasn't been tested adequately. The American College of Obstetricians and Gynecologists has disputed the usefulness of the procedure, stating in August 2017 that "[c]laims regarding abortion 'reversal' treatment are not based on science and do not meet clinical standards."

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Seven states with Republican governors have enacted such laws, starting with Arkansas in 2015, and Oklahoma's GOP-controlled legislature recently approved a measure. Kelly was elected last year and took office in January after the state imposed a raft of new abortion restrictions under her Republican predecessors Sam Brownback and Jeff Colyer.

Other states, including Kentucky, Mississippi and Ohio, have moved to ban abortions when a fetal heartbeat is detected, as early as the sixth week of pregnancy. Kansans for Life, the state's most influential pro-life group, has long favored an incremental approach and restrictions that would survive court challenges.

The Associated Press contributed to this report.