MORE TUESDAY COVERAGE Candidates tweak message for New Hampshire terrain Candidates charge onto N.H. airwaves Bradley appeals to independent New Hampshire voters Republicans look for spirited contest in N.H. Abortion issue dogs McCain in New Hampshire Caucuses over, presidential candidates flee to New Hampshire Tax issue boosts Forbes coming into New Hampshire Snow keeps Keyes from campaigning in N.H. Ad accuses McCain of working to cover up live POW data

"We're not going to dignify that ad with a response," said Mike Dennehy, McCain's regional campaign director.

The ad, in The Union Leader of Manchester, accused the Arizona senator of working to keep POW documents sealed.

"If released to the public, would these documents prove him to be an authentic war hero or a traitorous collaborator?" it asked.

The ad's accusations are not new.

McCain, a North Vietnamese prisoner of war for more than five years after his Navy jet was shot down, has broad support among veterans, including other former POWs.

But a few ex-POWs have castigated McCain and others for supporting U.S. diplomatic relations with Vietnam and for dismissing reports that some Americans were left behind alive when other POWs were brought home in 1973.

When two demonstrators made similar claims last summer while McCain was campaigning in New Hampshire, fellow POW James Stockdale, a retired admiral, shot back in a letter to The Union Leader.

"John McCain is tough as nails. He never disappointed me. I would go to hell with him again," wrote Stockdale, the senior Navy officer held captive in North Vietnam.

Jeremiah Denton, another fellow POW who also is a retired admiral, offered similar praise in a statement released before the latest anti-McCain ad.

"With many months of suffering from near-fatal wounds, he never lost the will to resist," Denton said. "He was an outstanding resister and an enterprising contributor to the overall morale" of other POWs.

Tuesday's ad claims that McCain, as a member of a Senate investigation in the early 1990s, belittled and threatened witnesses who claimed that live prisoners were left behind.

The report of the Senate investigation, released in early 1993, said there was hope, "but no compelling evidence," that a few dozen American soldiers might remain alive in Southeast Asia.

The committee unanimously rejected allegations that Americans were "knowingly abandoned" by U.S. officials, or that there was a conspiracy of silence within the Pentagon about the fate of prisoners.

The committee blamed the Defense Department's "penchant for secrecy" and "ever-changing policies" for contributing to an atmosphere of "suspicion and doubt," however.

The ad was taken out by Col. Earl P. Hopper Sr. of Glendale, Ariz., according to George Stachokas, the newspaper's vice president for advertising. There was no answer at Hopper's home Tuesday.

The last line of the ad said it was sponsored by families of former POWs or servicemen missing in action and other concerned citizens. Hopper was listed as a source of further information.

Stachokas said the paper rejected sections of the original proposed ad, based on the advice of its lawyer. The ad cost $5,412.