Former Sen. Rick Santorum (R-Pa.) said he meant "nothing ill" toward Sen. John McCain (R-Ariz.) after suggesting that the Arizona Republican "doesn't understand" enhanced interrogation.

Santorum wouldn't back off his assertion that McCain was wrong for opposing the use of enhanced interrogation techniques such as waterboarding against suspected terrorists.

But Santorum, a likely Republican presidential candidate, said he didn't mean to disparage McCain, who endured torture as a prisoner of war in Vietnam.

"I think John McCain is a great man; he served this country well," Santorum said on the Steve Malzberg radio show. "I meant nothing ill toward John McCain; it was just a policy disagreement."

"No one understands torture and no one understands how torture works better than John McCain," he explained later on the Sean Hannity show.

Santorum said on Monday that McCain didn't know anything about enhanced interrogation.

"This idea that we didn’t ask that question while Khalid Sheikh Mohammed was being waterboarded, he doesn’t understand how enhanced interrogation works," the former Pennsylvania senator said of McCain on Hugh Hewitt's radio show.

Those comments drew stiff rebuke from McCain confidantes, including Mark Salter, who said on his Facebook page that he had "never met a dumber member" of the Senate than Santorum. 

Santorum said on Hannity's show that he hadn't spoken to McCain.