WATERTOWN, S.D., May 16 (UPI) -- Democratic presidential contender Barack Obama, campaigning in South Dakota, fired back at comments made by U.S. President George Bush and Sen. John McCain.

Obama spoke of his "dust-up over foreign policy" with Bush and McCain, the presumptive Republican nominee for president, before a crowd of several hundred supporters in Watertown, S.D., The Washington Post (NYSE:WPO) reported Friday.

"If George Bush and John McCain want to have a debate about protecting America, that is a debate I will have any time, any place," he said. "George Bush and John McCain have a lot to answer for."

"They're trying to scare you and trying to keep you from seeing the truth," the Los Angeles Times quoted Obama as saying, "and the reason is they can't win a foreign policy argument on the merits."

Obama also hit back against Bush for comments he made in front of the Israeli Knesset that compared those who want to negotiate with terrorists to Nazi appeasers. Some have taken the remarks as a swipe at Obama, who denied having any intention of negotiating with radicals and called the remarks "the kind of appalling attack that's divided our country and that alienates us from the world," CNN reported.