John Kerry's (search) Vietnam War service records run to multiple medal commendations and a notation of "conspicuous gallantry" in combat. President Bush's (search) file tracks the stateside career of a National Guard test pilot.

Yet the combat veteran is the one under attack as a wartime pretender in the race for the White House. It's a controversy — Democrats call it a smear — stirred by the president's allies and aimed at undermining Kerry's truthfulness, personal character and fitness for office as much as his claim to the medals he came home with.

Smear or not, the charges are spreading at the speed of talk radio, cable television and the Internet, and affecting the campaign in unpredictable ways.

"He's lying about his record," said one Vietnam veteran in a commercial by the Swift Boat Veterans for Truth (search) that aired recently in three battleground states.

"Lying about his first Purple Heart," said a second. "He lied to get the Bronze Star," added a third.

"He dishonored his country, he most certainly did," said another, as the attack takes on a slightly different tone.

"John Kerry cannot be trusted," another vet concluded.

Challenged on trust, truth and credibility, Kerry fought back Thursday, adopting the language of his detractors.

They are spreading "lies about my record," he said; Bush, he said, was allowing front groups to "do his dirty work."

White House spokesman Scott McClellan seized on that to accuse Kerry of "losing his cool" — presumably not a trait the voters seek in a commander in chief.

Democrats concede privately the Massachusetts senator has been slow to recognize the damage being done to his political standing by the attacks by a group of men who hold Kerry's post-combat anti-war activities in contempt. There were hints of it in polling, and a tacit acknowledgment in the strongly worded rejection of the claims and in the decisions of both the Kerry campaign and the Democratic party to air new ads on the subject.

In a University of Pennsylvania National Annenberg Survey, more than half of those surveyed said they had either seen the ad aired by Kerry's detractors or heard of it. "Unfit for Command," a book detailing the Swift Boat Veterans' accusations, was No. 1 Saturday on Amazon.com's best seller list. A CBS poll said independent voters were split on whether the allegations were believable, and noted a shift in veterans toward Bush.

Like Kerry, the president faces continuing questions about his service during the Vietnam era.

So far, though, the president's critics haven't elevated it as a campaign issue, preferring to stress domestic concerns such as the economy, health care and education. In his speech Thursday, though, Kerry said he was more than willing to take up the issue with Bush personally. "Well, if he wants to have a debate about our service in Vietnam, here is my answer: 'Bring it on."'

It's unlikely the president will. There are lingering questions about whether Bush reported for National Guard duty over a three-month period in 1972. He was in Alabama at the time, having left Texas to work on a political campaign. The most recent batch of records, released on the eve of Kerry's nominating convention this summer, were inconclusive.

Kerry used his four-day Democratic National Convention to establish an identity as a war-wounded veteran who is now ready to take command in an era of terrorism. Oft-repeated charges to the contrary — true or not — may erode his claim and weaken his challenge to the president at a time when polls show a tight race.

"John Kerry has showed he's earned the trust of the nation to be commander in chief coming out of the (Democratic) convention," says spokesman Michael Meehan. "Republicans don't know what to do with themselves, so they will do anything, including a smear book, smear television ads paid for by Republicans filled with anything they can to stop him."

A decision to air counter-commercials in Ohio, Wisconsin and West Virginia was public evidence of concern, a shift in strategy for a campaign that had hoped to husband its advertising money until after Labor Day.

"All these Viet Cong were shooting at me," former Green Beret Jim Rassmann said in Kerry's commercial, recounting the day he recalls being thrown out of Kerry's boat by a blast. "I expected I'd be shot. When he pulled me out of the river, he risked his life to save mine."

The 30-second ad also says Swift Boat Veterans for Truth is funded by Bush's "big money supporters." The group is financed in part by Houston homebuilder Bob J. Perry, a GOP donor.

The Democratic Party began airing a new commercial in 21 states Friday, a straightforward testimonial to Kerry's qualifications that featured retired Gen. Merrill A. McPeak, former Air Force chief of staff.

On Saturday, the Kerry campaign was releasing a Web video comparing the Swift Boat Veterans campaign to the bitter Republican primary battle between Bush and Sen. John McCain in 2000. The video, to be sent via e-mail to supporters, says, "George Bush is up to his old tricks."

The commercials created by Kerry's critics have spawned a continuing campaign back-and-forth as impenetrable as any fog of war.

Military records say that despite claims made by Larry Thurlow, one of the men in the anti-Kerry ad, Kerry's boat and several others came under fire on March 13, 1969, the day Rassmann was pulled from the river.

In reply, Thurlow issued a statement. "There was no hostile enemy fire directed at my boat or any of the five boats operating on the river that day," it said, adding that the evidence for the citation was drawn from a report that Kerry had filed.

In a story for Sunday editions, the Washington Post said its investigation could not substantiate that Kerry, in fact, had authored the report..

The paper said the initials "KJW" on the bottom of the report had been cited by critics as evidence Kerry had written it. But Kerry's initials are JFK and a review of other Swift Boat after-action reports by the newspaper also contained the "KJW" initials, describing incidents where Kerry was not present, according to the Post.

Another conflict involves George Elliott, who said in a sworn statement last month that Kerry was "not forthright" in Vietnam, including about the circumstances for which he earned his Silver Star.

Eight years ago, though, when Kerry's claim to the medal had been challenged, the same man stood at the senator's side at a news conference. "The fact that he chased an armed enemy down is not something to be looked down upon but it was an act of courage," he said.