When Republican Vincent F. Callahan Jr. was first elected to the Virginia House of Delegates in 1967, his current challenger, Democrat Sherman Ponder, was 10 years old.

And if their contest for the 34th District House seat boils down to a fight between youthful enthusiasm and the experience of age, it will suit both candidates just fine.

Ponder "seems like a perfectly nice guy," Callahan said recently. "I was about his age the first time I ran.

"But when I ran, I had been active politically and in lots of civic groups. He doesn't have any community background. The Democrats didn't even know who he was until he ran."

Ponder also describes Callahan as "a nice, amiable guy," but quips, "He's running on his accomplishments during his tenure. Can you name one?"

Referring to a vote by House Republicans two years ago that removed Callahan as minority leader, Ponder said, "He's the first guy I know to be demoted from a senior leadership position by members of his own party.

"They didn't demote him because he was unethical. They demoted him because he was ineffective."

Personal ability has become a dominant campaign issue in the 34th District, a prosperous slice of northeast Fairfax County that includes parts of McLean and Falls Church and lies almost entirely inside the Beltway.

Politically, the 34th is a swing district. It has gone Democratic in the past two campaigns for governor but overwhelmingly favored President Reagan in 1984.

In this fall's House race, local politicians say, Callahan's established track record and support among GOP regulars make him the favorite.

But Ponder, 30, a self-employed insurance agent, is fighting back in classic underdog style.

Dubbing himself "the shoe-leather candidate," he is waging a low-budget race that relies on a staple of local politics: door-to-door campaigning.

Ponder estimates that he has visited more than 10,000 households in the district and will have hit more than 14,000 before Election Day.

He says he will probably go through four pairs of shoes, and has already lost 25 pounds.

Callahan expects to enjoy a clear advantage over Ponder in fund raising.

While Ponder says he has raised less than $5,000, Callahan has collected $26,000.

Ponder is hoping to eventually raise around $12,000, while Callahan is shooting for more than three times that amount, $40,000.

Ponder's grass-roots quest has almost gotten him arrested.

When the manager of a McLean apartment complex decided that a "No Soliciting" rule applied to politicians as well as salespeople, Ponder felt that his right to free speech was being violated and decided to go to jail as an act of protest.

He changed his mind after learning that trespassing carried a maximum penalty of a year behind bars.

"Maybe Gandhi could do it, but I can't," he quipped. "If I had just been thrown in a cell, that would be the end of me for this election."

Callahan, 55, is taking a more low-key approach.

His version of door-knocking is keeping to a regular schedule of civic clubs and political events.

"I'm pretty well-known among the people who vote in this district," he said. "I've lived here for 32 years. I belong to everything in sight. The campaign season never really ends."

Callahan publishes five defense industry newsletters and works out of his home.

His interest in defense is also reflected in his extensive collection of military history books and memorabilia.

Callahan's political career began in 1965, when he ran unsuccessfully for lieutenant governor at a time when the Democratic Party dominated statewide politics.

Callahan was elected to the House two years later and has remained there since.

"When I first went to Richmond, there were three people to represent all of Fairfax County, including the cities," Callahan said.

"Now the county alone has pieces of 12 House districts. The growth in population has been phenomenal, and Northern Virginia's political influence has grown along with it."

Callahan lost his job as House minority leader in 1985, when his fellow Republicans handed the position to a legislator who was considering a race for governor.

But Callahan says his membership on several powerful committees, including the Appropriations Committee, is a plus for his district.

"Northern Virginia Community College and George Mason University have done very well for themselves lately, and I'll take a lot of credit for that," Callahan said. "They've been able to expand because they've had the money they need."

Ponder challenges Callahan's claim, pointing out that as a member of the House's Republican minority, Callahan has little influence with the legislature's Democratic majority. Ponder contends that because of his party affiliation, he could accomplish more for his district.

Ponder also says that Callahan and other lawmakers have not taken adequate steps to control population growth and spiraling traffic problems in Northern Virginia.

He has attacked developers, saying "the unscrupulousness of a few greedy men is destroying our neighborhoods," and says the state should pass legislation that would require developers to pay more of the cost of new roads, schools and government services.

Callahan disagrees. "Public facilities serve all the people, and they should be built with taxpayers' money," he said. "Builders aren't going to pay the cost of anything. If we try to shift the burden, new people moving in will have to pay more."