By Malathi Nayak
WASHINGTON (Reuters) - President Barack Obama criticized Republican presidential candidates on Saturday for not defending a gay American soldier who was booed by the crowd at a Republican debate last week.
"We don't believe in standing silent when that happens," Obama said in the keynote address at the annual convention of the Human Rights Campaign, the largest U.S. gay lobby group.
In his remarks, Obama hailed the repeal of the military's "don't ask, don't tell" policy, and urged the Congress to repeal the Defense of Marriage Act, a 1996 law that defines marriage as between a man and a woman.
But, as he has done in the past, Obama stopped short of endorsing same-sex marriages. He says his views on the subject are still evolving.
Obama found an opportunity to attack his Republicans rivals indirectly. He has been seeking to rally his liberal base of support as he campaigns for re-election in November 2012 with his poll numbers down and Americans in general unhappy with his handling of the economy.
In Orlando, Florida, last week, the audience at a Republican presidential candidate debate booed after a soldier in Iraq, Stephen Hill, asked via video about the repeal of the 1993 law that banned gays from serving openly in the military.
"You want to be commander in chief?" he asked. "You can start by standing up for the men and woman in uniform" and support them even when it is not politically convenient.
Republican candidates Michele Bachmann and Rick Santorum, among others, have said they would keep the "don't ask, don't tell" law in place.
Obama drew a sharp line between Democrats and conservatives.
"I don't have to tell you there are those who don't want to just stand in our way, they want to turn the clock back, who want to return to the days when gay people couldn't serve the country openly, who reject the progress that we've made," Obama said.
"We're not about restricting rights and restricting opportunities. We're about opening up rights and opening up opportunities," he said.
Obama also urged the activists to help him persuade Congress to pass his $447 billion jobs bill, which is at risk of stalling.
(Writing by Steve Holland; Editing by Eric Beech)