(CNSNews.com) - Some of John Kerry's former swift boat crewmates will have a high-profile role at the Democratic National Convention later this month, as they attempt to portray Kerry as a decorated Vietnam War hero. But an even larger number of veterans say that's not the case.

As news spread Tuesday of the convention's framework, members of a group called Swift Boat Veterans for Truth dismissed the Democrats' plans. On the last night of the convention, an undisclosed number of Vietnam veterans plan to endorse Kerry.

"Preceding John Kerry and playing an important role will be his swift boat crewmates, who have stood by Kerry for more than 30 years since Kerry led them through the dangerous waters of Vietnam's Mekong Delta," a Democratic press release said.

A number of the veterans will speak glowingly about Kerry. Jim Rassman, a Green Beret who has said Kerry rescued him from a Vietnam river in 1969, will lead the group.

Members of the Swift Boat Veterans for Truth were quick to dismiss the effort, which they said amounted to a public relations push by the Kerry campaign to remake the candidate into a war hero despite lingering questions about his actions in Vietnam.

"The facts are that 250 of Kerry's former shipmates, including 17 of the 24 officers in his division, signed a public letter saying he's not fit to be the commander-in-chief," said retired Rear Adm. Roy Hoffmann, who commanded the fleet of swift boats during Kerry's tour of duty.

Hoffmann is one of the most outspoken veterans to oppose Kerry's candidacy. During a May 4 press conference announcing the Swift Boat Veterans for Truth, he called Kerry a "loose cannon" because of his actions in Vietnam. After the war, Kerry adopted an anti-war position that angered many veterans.

Since the press conference, which attracted throngs of reporters and a quick rebuttal from the Kerry campaign, the Swift Boat Veterans for Truth have continued to work behind the scenes on ways to refute Kerry's claims about his Vietnam service.

One veteran who served alongside Kerry in another swift boat said the story of his rescue of Rassmann was exaggerated.

"I have an eyewitness, firsthand account of what happened," said Larry Thurlow, who commanded a swift boat. "And the story he now tells is so drastically far from what actually happened, if I didn't know he was recounting this particular day, I wouldn't even recognize the story."

It was on that day that Kerry sustained an injury to his arm that resulted in a Purple Heart medal. Thurlow said Kerry didn't deserve that medal based on his recollection of events that day. Thurlow said the rescue wasn't nearly as dangerous as Kerry has described.

"He's a rhinestone cowboy," said John O'Neill, a veteran who helped organize Swift Boat Veterans for Truth. "He literally is a guy who parades around and pretends to be something he's not. He was in Vietnam for four months; everyone else was there for a year. He obtained three Purple Hearts from self-inflicted wounds. And then he left."

O'Neill also criticized the mainstream news media for not looking outside Kerry's small circle of Vietnam supporters. The actual number who will appear at the Democratic convention wasn't disclosed, but O'Neill said it would be nowhere near the number of critics.

"The media continue to go to the same six or seven people, although 254 people have signed our letter," O'Neill said. "They're ignoring that."

Kerry's campaign headquarters didn't respond to CNSNews.com's offer to rebut the veterans' charges. But in response to the May 4 event, at which nearly 20 veterans spoke, Kerry supporters hastily called a press conference.

Wade Sanders, a former deputy assistant secretary of the Navy, said Swift Boat Veterans for Truth has a partisan motive in its attack of Kerry, a charge the Republican National Committee dismissed at the time.

"I don't think that many of the people who are following this gentleman, Capt. (sic) Roy Hoffmann, really understand the political implications of what's going on here, I mean what's fronting this," Sanders said.

But each of the veterans interviewed by CNSNews.com Tuesday were adamant that their disapproval of Kerry was driven solely by personal knowledge of him and his actions.

"We're taking him on, not because of his politics, but because he's lied about us and he specifically lies about his own actions," Thurlow said. "He's just blown them out of proportion to the point where it's ridiculous. We're madder than hell and we're not going to take it anymore."