JEFFERSON CITY –  Missouri Gov. Jay Nixon vetoed legislation Wednesday that would have required a 72-hour wait for women seeking abortions, asserting that legislators showed a "callous disregard for women" by granting no exception for rape and incest victims.

Republican legislators quickly vowed to override the Democratic governor's decision, and they may have the numbers to do so. The GOP-led Legislature approved the plan earlier this year only one vote shy of the supermajority needed to undo a veto.

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 rape and incest victims, and people younger than 14.

Nixon had allowed prior Missouri abortion restrictions to take effect, but drew a line with the longer waiting period.

"This extreme and disrespectful measure would unnecessarily prolong the suffering of rape and incest victims and jeopardize the health and wellbeing of women," Nixon said in a written statement.

Missouri law currently requires a 24-hour wait between when a woman consults a physician and receives an abortion, with an exception only for medical emergencies. 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 Wednesday that the failure to include those exceptions "demonstrates a callous disregard for women who find themselves in horrific circumstances."

Majority Republicans had several members absent but picked up support from nine Democrats when the House gave final approval to the bill 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.

"I'm confident that we've got more than ample numbers to override the governor's veto," said Rep. Kevin Elmer, a Republican from Nixa who sponsored the legislation.

In a memo to lawmakers, Nixon wrote that the bill appears to be based on a "paternalistic presumption that rape and incest victims are somehow unable to grasp the horror that has befallen them, and that government must force them to take more time to come to grips with their plight."

Sen. David Sater, one of the sponsors of the measure, had argued against the rape and incest exception. He said Wednesday that Nixon was effectively placing a lower value on the life of a child conceived through rape than one conceived consensually but perhaps unintentionally.

"They're both equal in God's eyes. Those children are both of equal importance," said Sater, a Republican from Cassville.

Missouri law already requires doctors to provide a variety of written information to women wanting abortions and to give them the opportunity to hear the fetus' heartbeat on an ultrasound.

Nixon cited those existing provisions while asserting that a longer waiting period would serve no purpose "other than to create emotional and financial hardships for women." He said the longer wait also could increase the risk of complications for women. Because of those concerns, Nixon said he would have vetoed the bill even if it had a rape-and-incest exception.

There were 5,624 abortions performed in Missouri in 2012, the latest year for which state figures are available, marking a continued decline in recent years.

Missouri currently has only one clinic performing elective abortions, a Planned Parenthood affiliate in the St. Louis area. Planned Parenthood also performs abortions at a Kansas City area clinic located in a Kansas suburb.

Paula Gianino, president and CEO of the political arm of Planned Parenthood of the St. Louis Region and Southwest Missouri, praised the governor's veto. She said the legislation "would block access to safe, legal abortion and make it more difficult for women to get the care they need."