Republican presidential candidate Herman Cain admits he should have spoken out when the audience booed a gay U.S. soldier at a Republican candidates' debate last month.

The soldier was booed when he asked the candidates if they would try to get around new rules allowing gays to openly serve in the U.S. military.

Cain said on U.S. television Sunday that it would have been appropriate to say something to the audience.

Senator and former Republican presidential nominee John McCain said that the candidates should have responded to the booing.

He said they were probably thinking about how to answer the gay soldier's question instead of responding to the hostile reaction. He said that none of the Republican candidates likely agreed with the boos.

Speaking to a gay rights group Saturday, President Barack Obama chastised the Republicans for their silence. He said anyone who wants to be U.S. commander-in-chief has got to stand up for men and women in uniform, even when it is not politically convenient.

The Pentagon scrapped the so-called “don't ask, don't tell” rules about gays in the military last month. Under the old policy, gays could serve, but not disclose their sexuality. Those discovered to be homosexuals or lesbians were immediately discharged.