Kerry's campaign in Wisconsin had been publicizing a four-day "Tour of Honor" featuring Harkin, former Sen. Max Cleland (search) and other veterans. Harkin was to speak in Eau Claire on Thursday but withdrew for "logistical reasons," said Lesley Sillaman of Kerry's Wisconsin campaign.
She denied that Harkin was "pulled from the lineup," as Republicans suggested.
"Not at all. That's absolutely not the truth," Sillaman said.
Harkin on Friday said he was unaware of any tour with Cleland, stood by his remarks about Cheney and said he will continue to speak out whenever Republicans "impugn the honor and integrity of a veteran."
Harkin ripped Cheney after the vice president criticized Kerry's comments about pursuing a "more sensitive war on terror."
"When I hear this coming from Dick Cheney, who was a coward, who would not serve during the Vietnam War, it makes my blood boil," Harkin said.
Although Harkin said Friday he wasn't "castigating Cheney for not serving in the military," Harkin's remarks came at a time when the Kerry presidential campaign was calling for civil dialogue during the campaign.