2012 Election
Gary Johnson, the former governor of New Mexico, participated in Thursday's Republican presidential candidates' debate in Orlando, Fla. REUTERS

Republican presidential candidate Gary Johnson slammed the booing of a gay soldier at last week's Fox News/Google GOP Debate, telling Rev. Al Sharpton in an MSNBC interview that he regrets not speaking up during the incident.

During the MSNBC interview on Friday, Johnson, the former governor of New Mexico, told Sharpton that he had to resist the urge to pound his fist in anger when the crowd booed Stephen Hill, a gay soldier who asked fellow long-shot candidate Sen. Rick Santorum, R-Pa., about open service in the military in commemoration of last week's repeal of Don't Ask, Don't Tell.

In response, Santorum -- who, at the time, did not comment on the jeering -- characterized open service as a special privilege and said he would reinstate Don't Ask, Don't Tell if elected president.

It should not be an issue. Leave it alone. Keep it to yourself - whether you're heterosexual or homosexual, Santorum said.

Santorum later said he did not approve of the booing, claiming that he was unable to hear it from the stage. However, the fact that Johnson obviously could casts doubts on Santorum's sincerity.

While discussing the incident with Sharpton, Johnson said the booing was not right but admitted he was nervous about bringing it up at the event since he had been excluded from other Republican debates.

If I have one regret from last evening, it's that I didn't stand up and say, you know, you're booing a U.S. serviceman who is denied being able to express his sexual preference? That's not right. That's not right, and there's something very, very wrong with that, he said.

Johnson said he believes Don't Ask, Don't Tell should have been repealed a long time ago and derided other examples of unexpected audience outbursts at previous GOP debates. For instance, Johnson said he doesn't think there is any question that the U.S. puts innocent people to death, in reaction to an audience applauding Texas' extensive prisoner execution rate since Rick Perry became governor in 2000 at the Sept. 7 debate.

Moreover, he said he was disturbed by the cheers invoked at the Sept. 12 debate when moderator Wolf Blitzer asked the candidates a hypothetical question about the fate of uninsured Americans, asking Are you saying society should just let him die?

We're a country of compassion. These are the people that we want to help. I'm in the camp that really believes that government perhaps is the only entity that's available for those that are truly in need, Johnson said.

Johnson is a fiscally conservative, socially liberal Republican who is an advocate of limited government. He served as governor of New Mexico between 1995 and 2003, where he was celebrated by Republicans for slashing the size of the state government and leaving the state with a $1 billion budget surplus at the end of his second term.