Republican legislators quickly vowed to override the Democratic governor's veto when they convene in September, and they may have the numbers to do so. The GOP-led Legislature approved the plan by large margins earlier this year.
The stricken measure would have made Missouri just the third state nationally to require a three-day waiting period for abortions, along with South Dakota and Utah. Utah's law includes an exception for victims of rape and incest, and people younger than 14.
"This extreme and disrespectful measure would unnecessarily prolong the suffering of rape and incest victims and jeopardize the health and wellbeing of women," the Democratic governor said in a written statement.
An override would require a two-thirds vote in both chambers. The measure originally passed the House 111-39, getting two votes more than would be needed for an override. The 22-9 Senate vote fell one vote short of that threshold, but one Republican senator was absent.
Missouri law currently requires a 24-hour wait between when a woman consults a physician and receives an abortion, with no exception for rape or incest. During debate on the bill to triple the waiting period, Republican senators defeated a Democratic amendment that would have added a rape and incest exception.
Nixon said the failure to include those exceptions "demonstrates a callous disregard for women who find themselves in horrific circumstances."
Sen. David Sater, one of the sponsors of the measure, had argued against the rape and incest exception. He said Wednesday that he was disappointed by Nixon's veto.
Abortion "is an irreversible and permanent decision, and taking the time to think about the consequences is not unreasonable or a burden," Sater, R-Cassville, said in a written statement.
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