Presidential candidates in Manchester, New Hampshire, Feb. 6, 2016. Reuters

Republican candidates defended women's right to serve in combat roles and be drafted for the military during Saturday night's GOP debate in New Hampshire. Their remarks came as the military is opening up combat roles to women for the first time.

"I do believe that selective service should be opened up for men and women," Florida Sen. Marco Rubio said. Fomer Florida Gov. Jeb Bush agreed. “If women can meet … the minimum requirements for combat service, they ought to have the right to do it, sure," he said.

New Jersey Gov. Chris Christie also embraced allowing women to sign up for the draft. “Can I be really clear on this? Because I am the daughter of two daughters, one of them is here tonight,” he began. “What my wife and I have taught our daughters right from the beginning, that their sense of self-worth, their sense of value, their sense of what they want to do with their life comes not from the outside but from within.”

“And if a young woman in this country wants to go and fight to defend her country, she would be permitted to do so,” Christie said. “There’s no reason why one young woman should be discriminated against from registering for the selective service.”

Social media users reacted strongly against the idea.

The debate, hosted by ABC News and the Republican National Committee, included business mogul Donald Trump, Texas Sen. Ted Cruz, neurosurgeon Ben Carson and Ohio Gov. John Kasich. To make it on stage, the candidates needed to place among the top three in the Iowa caucuses Monday or place among the top six either nationally or in New Hampshire polls. Carly Fiorina was excluded after she placed seventh in Iowa, garnering less than 2 percent of the vote.

Christie was particularly feisty Saturday night, slamming his rivals who have served time in Congress. "First, let's remember something. Every morning when a United States senator wakes up, they think about what kind of speech can I give, or what kind of bill can I drop? Every morning, when I wake up, I think about, what kind of problem do I need to solve for the people who actually elected me?" Christie said at one point.

The idea of requiring eligible women in the United States to sign up for the military draft has grown in recent weeks. Rep. Duncan Hunter, R-Calif., a Marine veteran, and Rep. Ryan Zinke, R-Mont., a retired Navy SEAL, filed the Draft American’s Daughters Act this week to encourage debate over the military’s historic move to fully integrate female troops into all combat roles. “If this administration wants to send 18, 20-year-old women into combat, to serve and fight on the front lines, then the American people deserve to have this discussion through their elected representatives,” Hunter said in a released statement.

Last week, Army Chief of Staff Gen. Mark Milley said women should register for the draft. Young men in the U.S. must register, although there is no draft.