The measure would make several modifications to Missouri gun laws.
The main section of the bill would authorize school districts to empower teachers to carry concealed weapons on school grounds.
Another provision would prohibit local government from banning open carry for persons with a concealed weapons permit.
Missouri tourist areas Kansas City and Lake of Ozarks have banned open carry. Supporters have argued seeing persons walking around with pistols in outside holsters harms tourism.
In both the House and Senate, the measure cleared the legislature with fewer than the two-thirds vote that would be required for a veto override -- 109 in the House and 23 in the Senate.
The Missouri House passed the bill with more than the 109 votes that would be needed for an override -- 111-28.
In the Senate, the bill fell two votes short of the 23 votes necessary for an override (21-7). However, three Republican senators were not present for the vote.
In his veto letter, Gov. Jay Nixon said the provision allowing for arming of teachers could not make schools safer.
"I have supported, and will continue to support, the use of duly authorized law enforcement officers employed as school resource officers in schools." Nixon wrote. "This bill, which would create new mechanism for the arming of teachers, would not make schools safer."
The bill would allow school districts to designate staff as school protection officers. The school district has a closed door meeting to discuss whether a school protection officer carries a concealed firearm or self-defense spray.
Staff wanting to become school protection officers would have to make written requests to the district superintendent and have a valid conceal carry permit. The Department of Public Safety would have to be notified of any designation of school protection officers. A list school protection officers available to law enforcement agencies.
The bill's sponsor -- Sen. Will Kraus, R-Jackson County - said that Nixon was misinformed with his veto of the bill.
"I think the governor is misinformed, our current law allows teachers to carry under the school," Kraus said. Kraus argued that the bill would take school safety a step forward with additional training.
The bill also would restrict local housing authorities from prohibiting tenants from possessing firearms in their residences.