President Barack Obama is pushing back on rival Mitt Romney's suggestion that the president has apologized for the United States on the world stage. Obama called the accusation the "biggest whopper" of the campaign.

The two men were sparring over foreign policy Monday in the final debate before Election Day.

Obama said he would not allow Iran to develop a nuclear weapon and had coordinated an international coalition to impose economic sanctions on Tehran. Obama said that under his presidency, the world is more united and Iran has been weakened.

Romney insisted Obama had apologized for the U.S., noting the president had given a speech in Egypt early in his term saying America had been "derisive" and at times had dictated to other nations.