A large slice of the US electorate is at stake; the country's 27 million military veterans account for one in five voters. And the United States has 1.4 million active military personnel, plus 1.2 million National Guard members and reservists.

Soldiers and veterans have traditionally backed Republican candidates, and Bush has touted his role as commander in chief of the Iraq war and his response to the September 11, 2001, attacks to court military voters ahead of the November 2 election.

Kerry, in turn, has showcased his record as a decorated Vietnam War veteran. Veterans joined him on stage when he accepted the Democratic Party's nomination at its national convention last month.

While Kerry fought in Vietnam, Bush stayed in the United States as a member of the Texas Air National Guard.

Kerry has slammed Bush's record in Iraq, pointing to his failure to garner a larger international coalition in a war that has claimed the lives of some 950 US soldiers since it was launched in March 2003.

Kerry seemed to have gained ground among veterans. After last month's Democratic National Convention, he was tied with Bush at 46 percent among this group.

But a CBS News Poll released Thursday reported Bush ahead 55 to 37 percent, with Kerry's military record under relentless assault by a veterans group calling itself Swift Boat Veterans for Truth (SBVT).

The group has aired television spots alleging Kerry lied to obtain two of his five medals and that he betrayed US forces still in Vietnam by charging after he returned to the United States that US troops committed atrocities.

A National Annenberg Election Survey poll released Friday reported that more than half the country had seen or heard about the ads, though they were released in just a handful of states.

Kerry urged Bush to condemn the ads.

"The president keeps telling people he would never question my service to our country," he said Thursday. "Instead, he watches as a Republican-funded attack group does just that. Well, if he wants to have a debate about our service in Vietnam, here is my answer: Bring it on!"

While the White House has consistently denied any links between Bush's campaign and the SBVT, it said it respects Kerry's wartime service. But it refused categorically to repudiate the charges against him.

"We've already said we weren't involved in any way in these ads," White House spokesman Scott McClellan said Friday. "We've made that clear. I do think that Senator Kerry losing his cool should not be an excuse for him to lash out at the President with false and baseless attacks."

While Kerry defends his record, Bush has proposed new initiatives favoring the military.

On Monday, he announced a plan to bring back to US bases up to 70,000 US soldiers deployed in Europe an Asia over the next decade, saying it "will reduce the stress on our troops and our military families."

His 2005 federal budget offers a 3.5 percent salary increase for soldiers, a higher raise than the one slated for other government employees.

As he campaigned this week in Wisconsin, one of states considered key for victory in the election, Bush proposed boosting monthly education benefits for National Guard members and reservists mobilized for more than 90 consecutive days.

The extension of troops' stay in Iraq has brought some discontent.

An army reservist is suing Defense Secretary Donald Rumsfeld and top military officials over a retention policy that allows the Pentagon to keep troops on active duty in Iraq even after their designated service time expires.

WAR.WIRE