Appearing on CNN on Tuesday night, Robertson recalled a private meeting with Bush before the Iraq war began, at which he said the president asserted there would be no casualties.
"I warned him about this war. I had deep misgivings about this war, deep misgivings. And I was trying to say, Mr. President, you better prepare the American people for casualties," Robertson told CNN's Paula Zahn.
But Bush said, " 'Oh, no, we're not going to have any casualties,' " Robertson related.
During the meeting, Bush "was the most self-assured man I ever met in my life," Robertson said. "You remember Mark Twain said, 'He looks like a contented Christian with four aces.' He was just sitting there, like, 'I'm on top of the world.' "
Robertson's comments quickly became an issue in the presidential campaign and put the White House in the awkward position of denying comments from one of Bush's most prominent supporters.
"I think he must have either misunderstood, misheard or been confused about what the conversation was because I've never heard the president say anything of the sort, and he wouldn't have," Karen Hughes, a senior Bush advisor, told reporters. White House spokesman Scott McClellan said: "Of course the president never made such a comment."
Bush strategist Karl Rove told reporters that he was in the room for the Feb. 10, 2003, meeting, and that Robertson was incorrect in his recollection.
"I was right there," Rove said.
Robertson issued a two-paragraph statement confirming his support for Bush, but he did not withdraw his comments.
Robertson's remarks sparked a stern reaction Wednesday from the campaign of Democrat John F. Kerry, which has criticized Bush for his refusal, as recently as in the second presidential debate, to acknowledge having made mistakes during his time in office.
"We believe President Bush should get the benefit of the doubt here, but he needs to come forward and answer a very simple question: Is Pat Robertson telling the truth when he said you didn't think there'd be any casualties, or is Pat Robertson lying?" said Kerry spokesman Mike McCurry.
More than 1,100 U.S. servicemen and women have died in the war, and thousands more have been injured.
Robertson, who is founder of the Christian Broadcasting Network and host of its program "The 700 Club," talked about his 2003 meeting with Bush as part of a larger conversation about how he believed "God's blessing is on" the president, despite Bush's "goofs and gaffes."
Robertson has made similar comments in the past.
On June 22, the former GOP presidential contender said on the MSNBC program "Hardball" that "I warned the president. I only met with him once. I said you better prepare the American people for some serious casualties. And he said, 'Oh, no, our troops are, you know, so well-protected, we don't have to worry about that.' "
Robertson declined through a spokeswoman to comment on the flap over his remarks.
When Zahn asked Robertson how evangelicals who might disagree with Bush on the war and other policies could still vote for him, Robertson seemed to stop just short of calling the president the lesser of two evils.
"Well, you know, you don't run against perfection. It's two fallible people," Robertson said. "So it's either the lesser of the evil or the best of second -- the best -- whatever."