A Republican bill to allow teachers to carry concealed weapons in Colorado schools was defeated in a Senate committee Monday, with Democrats dismissing arguments that it would make children safer from massacres like the Sandy Hook Elementary School shooting.

Senate Bill 9 failed on a 2-3 party-line vote in the Judiciary Committee on a day when more than 100 demonstrators gathered outside the Capitol to rally in favor of stricter gun controls.

With Democrats now back in charge of both chambers of the legislature, and in the wake of the Aurora and Sandy Hook mass shootings, there is a newfound push for gun-control measures that has cheered supporters, who have gotten little traction on the issue for years, even among Democrats.

Under current law, concealed weapons are prohibited at schools, but the bill would have let local school boards allow their teachers and other school employees to carry concealed weapons in schools if they have permits. The school boards could require greater training for their employees if they wanted.

State Sen. Scott Renfroe, R-Greeley, a former school-board member and a sponsor of the bill, said that ever since the 1999 Columbine massacre, he has been thinking of how to stop school shootings.

“It’s a tragedy of what keeps happening over and over and over,” Renfroe said. “Frankly, it’s clear that gun-free zones don’t work.”

State Sen. Ted Harvey, R-Highlands Ranch, a co-sponsor of the bill, said his wife is a teacher and his kids attend public school.

“My wife and my kids are sitting ducks,” Harvey said, arguing that allowing teachers to carry concealed weapons would give children a better chance to survive if a shooter enters a school.

That was also the argument from Bethany Christiansen, a teacher from Greeley, who has a concealed-carry license and who testified in favor of the bill.

“Teachers being allowed to carry guns in school is something that will keep our children safe,” Christiansen said.

But state Sen. Jesse Ulibarri, D-Commerce City, asked whether armed teachers might just end up shooting their students, who would be in a crossfire.

“I want to make sure that I’m not allowing something worse to happen,” Ulibarri said.

Opponents of the bill included the Colorado Education Association, the state’s largest teachers union; and Eileen McCarron, a retired math teacher and the president of Colorado Ceasefire, a group that argues for greater gun control.

“We Coloradans do not wish to turn our school into prisons or our teachers into prison guards,” McCarron said.

Tim Hoover: 303-954-1626, thoover@denverpost.com or twitter.com/timhoover