Democratic presidential candidate John Kerry on Saturday night urged President Bush to "stand up and stop" what he called personal attacks on him over his combat record in Vietnam.

A recent attack on the war record of Sen. John Kerry has heated the presidential politics surrounding the military records of both Kerry and President Bush.

At a fundraiser, attended by about 750 people, Kerry said the attacks by a group of Vietnam veterans and former Swift Boat commanders have intensified "because in the last months they have seen me climbing in America's understanding that I know how to fight a smarter and more effective war" against terrorists.

The White House and the Bush campaign have denied any direct connection with the Swift Boat group. "The president has made it repeatedly clear that he wants to see an end to all" advertising from outside groups, said Brian Jones, a Bush campaign spokesman.

But on Saturday, a former POW, retired Col. Ken Cordier, resigned as a volunteer from the Bush campaign's veterans' steering committee after it was learned that he participated in an anti-Kerry ad sponsored by the Swift Boat group. The ad criticizes Kerry's congressional anti-war testimony in the 1970s alleging U.S. troops engaged in atrocities in Vietnam.

"Col. Cordier did not inform the campaign of his involvement in the advertisement," the Bush campaign said in a statement. "Because of his involvement (with the group) Col. Cordier will no longer participate as a volunteer for Bush-Cheney '04."