Republican presidential candidate Rick Santorum tore into President Barack Obama today for apologizing for the burning of Qurans at a U.S. base in Afghanistan.

“There was nothing deliberately done wrong here. This was something that happened as a mistake,” the former Pennsylvania Senator said on ABC’s “This Week.” “Killing Americans in uniform is not a mistake. To apologize for something that was not an intentional act is something that the president of the United States in my opinion should not have done.”

The president’s apology, which came Thursday as two U.S. soldiers were killed in retaliatory protests, has become the latest political football in the Republican primary contest, bringing foreign policy into a dialogue that has revolved almost exclusively around the economy.

Former Massachusetts Gov. Mitt Romney, who is also running for the GOP nomination, said on “Fox News Sunday” that he did not approve of Obama’s language.

“With regards to the apology, I think for a lot people … it sticks in their throat,” he said. “The idea that we are there, having lost thousands of individuals through casualty and death. We’ve made an enormous contribution to help the people there achieve freedom, and for us to be apologizing at a time like this is something which is very difficult for the American people to countenance.”

Secretary of State Hillary Clinton, appearing on CNN’s “State of the Union,” defended the president’s decision, comparing it to similar actions taken by his predecessor, President George W. Bush.

“It was the right thing to do to have our president on record as saying: ‘You know, this was not intentional. We deeply regret it,’” she said.

When asked about her emphatic prediction Saturday that Obama would be re-elected, the former New York Senator and first lady acknowledged that she had ventured too far into politics.

“Probably my enthusiasm for the president got a little out of hand,” she said.

Earlier this week, Newt Gingrich also weighed in, described the apology as “astonishing.”

“If Hamid Karzai, the president of Afghanistan, doesn’t feel like apologizing, then we should say goodbye and good luck,” the former Speaker said while campaigning in Washington state. “We don’t need to be here risking our lives and wasting our money on somebody who doesn’t care.”

Robert Gibbs, a senior adviser to the Obama campaign, took the comments as an opportunity to ding Gingrich on his foreign policy credentials.

“I don’t think a lot of people are looking to Newt Gingrich for foreign policy advice,” he said in an interview today on CNN. “If there’s a problem on the lunar colony, he’ll be the first one we call.”