Sponsor Sen. Curt McKenzie, R-Nampa, said barring guns from campus strips students and faculty of their constitutional freedoms guaranteed by America's Founding Fathers.
The bill now goes to the House, where a similar measure passed muster in 2011. That's likely to happen again, meaning Idaho would join Colorado, Kansas, Mississippi, Oregon, Wisconsin and Utah among states that currently allow guns on campus. Gov. C.L. "Butch" Otter has pledged to sign the bill.
"It's the Legislature saying you have a constitutional right and you don't lose that right when you step onto a publicly held universality," McKenzie said.
When the 2011 House-passed bill failed in the Senate, foes said among their concerns were a lack of training and possible access by students who had been drinking.
McKenzie said he has addressed the concerns.
Under the current measure, only retired law enforcement and those with Idaho's enhanced concealed carry permit which requires an eight-hour training class and firing 98 rounds every five years would be allowed to have a gun.
The bill also bans firearms in dormitories and stadiums and carries harsher penalties for those who tote a gun while intoxicated or on drugs.
Three Republicans Sens. Shawn Keough of Sandpoint, Dan Johnson of Lewiston and John Goedde of Coeur d'Alene joined all seven minority Democrats in opposing the bill.
Sen. Marv Hagedorn, R-Nampa, also backed the bill, arguing it gives those on campus a way to protect themselves and acts as a deterrent to criminals.
"Bad guys don't know who's armed, who's not armed, who to attack, who not to attack," he said. "But they know on campus, that's a gun-free zone."
But Sen. Elliot Werk, a Boise Democrat who has been outspoken in his opposition for the bill, dismissed the idea that criminals were stalking college campuses for their next victim.
"If it were true that these gun-free zones made colleges less safe, then we would see higher crime rates on college campuses and the surrounding communities," he said.
In fact, the opposite is true.
Werk says that may not be for long if students who have guns let anger or alcohol cloud their judgment.
Sen. Jim Rice, R-Caldwell, said coddling people on campus wasn't his job. It was his job, he said, to preserve freedoms.
"We sometimes think our duty is to make everyone safe," Rice said. "It's to preserve liberty. It's not to make a society that's absolutely safe."
Heads of all eight of Idaho's public universities and colleges have spoken out against the bill, as has Boise Police Chief Mike Masterson.
That convinced Sen. Roy Lacey, D-Pocatello, who said the bill was only gaining steam because his colleagues didn't want to look weak on Second Amendment issues going into the May 20 primary election.
"Our university leadership says no, our local police department says no, our sheriff's department says no," he said. "We need to listen to those who are involved."