Republican presidential hopefuls Herman Cain and Michele Bachmann have both said they would reinstate waterboarding during interrogations of suspected terrorists, while rivals Ron Paul and Jon Huntsman both say they see the procedure as torture.
The Republican contenders split on Saturday night over whether waterboarding would be an effective tool in the war on terror.
Mr Cain said he does not support torture, but he would trust military leaders to determine what that means. He said he would return to waterboarding because he does not see it as torture.
Ms Bachmann says she supports the practice, while Mr Paul said it is illegal.
Mr Huntsman said waterboarding diminishes US standing in the world and undercuts the nation's values.
Republican contender Mitt Romney was not directly asked about the issue but added he would use whatever means necessary to protect America.
Later, three of the contenders said they would continue to hold terror suspects at the military prison at Guantanamo Bay.
Mr Cain, former senator Rick Santorum and Ms Bachmann all said they want to keep the prison open, allow the use of controversial techniques to interrogate terrorists and use military courts to try the terrorism suspects who are held there.
Governor Rick Perry said the US should continue to use enhanced interrogation techniques to save American lives overseas, without addressing Guantanamo Bay directly.
President Barack Obama has been trying to close the prison since the early months of his presidency.