WASHINGTON -- Democrats Wesley Clark and John Kerry are basing their presidential campaigns largely on military service that includes combat in Vietnam -- a distinctive qualification in a race full of candidates who came of age during the war but did not fight.

Their White House rivals did not serve in Vietnam, even though most turned 18 while young men were being drafted. They escaped combat with deferments for college, medical problems, fatherhood and by serving in the National Guard.

President Bush was the National Guard during the war and did not see combat.

Clark and Kerry mention their military service in nearly every campaign appearance, offering their credentials as evidence they are best prepared to lead the nation during the fight against terrorism.

Clark was an Army infantry officer and company commander in Vietnam. He rose to four-star general and supreme allied commander of NATO forces in Europe. Kerry was the skipper of a Navy swift boat in the Mekong Delta of South Vietnam.

Both men received the Purple Heart after being wounded in combat and were awarded the Silver Star for gallantry in action.

"Obviously we've had presidents who haven't had military experience," Kerry said in an interview. "I understand that. It's not a prerequisite. But we are living in a very different time."

Fewer veterans in office

Military service used to be almost a requirement for winning elective office. In 1977, nearly 80 percent of House members were veterans. Some 76 senators in 1983 were veterans. Today, just 28 percent of representatives and 35 senators have military experience.

Twenty-five of the 43 U.S. presidents have served in the military.

Pat Towell, a visiting fellow at the Center for Strategic and Budgetary Assessments, said the social inequities of the Vietnam draft probably kept many of today's current political leaders out of that war.

"Big surprise, the kids that were in the kinds of universities where you grow up and become a senator and run for president weren't drafted," Towell said.

An Associated Press review of the presidential candidates' Selective Service records shows that only Sen. John Edwards of North Carolina and Howard Dean were assigned a lottery number.

Edwards was assigned No. 178 for 1973, but the draft ended that year before his number was called.

Dean was assigned No. 143 for 1970 -- a number that was called up -- but he was rejected after a physical in February of that year. In an interview with the AP, Dean said he had known since he was in high school that he had an unfused vertebra, a condition called spondylolysis.

Dean tried to spell the condition during the interview, but got it wrong after three tries, even though he is a medical doctor and worked as an internist before entering politics. He laughed over his difficulty and defended himself by saying he is not a bone specialist.

Spondylolysis is a stress fracture of a vertebrae that is a common cause of back pain in teenage athletes. Dean said his back started bothering him when he was running track his junior year of high school.

Dean said he decided not to correct the problem because it would require an extensive operation with a long recovery time. But when he got his draft lottery number while an undergraduate at Yale University, he took his X-rays and a letter from his orthopedic surgeon to Fort Hamilton, an Army installation in Brooklyn, N.Y.

Dean said he wanted to find out if he would qualify for officer candidate school if he were drafted. He said he was relieved that the military physical disqualified him from service except in times of national emergency.

"I was not anxious to serve in Vietnam," said Dean, whose brother, Charles, died under mysterious circumstances in Laos during the Vietnam War. "I was opposed to the war and I was glad I was classified that way, but it was obviously not my decision."

Like Dean, anti-war candidate Dennis Kucinich was disqualified from serving because of a medical problem. The Ohio congressman said he has a heart murmur.

Kucinich said in an interview that he opposed the Vietnam War, but would have served if he could. He said as a child he was interested in going to one of the service academies and following in the footsteps of his father, a World War II veteran who had a silver plate in his knee from a combat wound and kept a Marine emblem hanging on the wall.

Kucinich has a sister and two brothers who served in the military. His brother Frank served in Vietnam.

"The heart murmur changed a lot," he said. "I graduated in '64, a class that took a lot of casualties. ... Sometimes you just have to say but for the grace of God go I."

Sen. Joe Lieberman of Connecticut and Rep. Dick Gephardt of Missouri each initially got 2-S deferments for undergraduate studies and then law school. After graduation, Gephardt joined the Missouri Air National Guard as a legal affairs officer and got a 1-D classification that kept him from being sent to Vietnam. Lieberman got a 3-A deferment for becoming a father.

Lieberman, Edwards and Gephardt did not respond to requests to be interviewed for this report.

Candidate Al Sharpton turned 18 on Oct. 3, 1972, just as the draft was winding down.