If you ask Carole L. Herrick what the race for the 34th District House of Delegates seat is all about, she responds quickly and with passion: It's about the need to impose more controls on handguns.

Pose the same question to John W. Foust, and he's just as certain that voters want to hear suggestions for slowing down the rapid growth that has clogged roads and classrooms.

So you would think that the Democratic primary between the two on Tuesday would offer a stark choice for voters looking to choose a challenger to longtime incumbent Republican Vincent F. Callahan Jr. (Fairfax).

Not so fast.

Yes, the two Democrats from McLean stress different priorities in their opening salvos. But look a little deeper and the differences ease markedly.

Take gun control.

Herrick, 58, believes passionately that there should be stricter controls on weapons. Even before the rampage at Columbine High School in Colorado, Herrick said, she advocated to stop the sales of weapons at gun shows and flea markets. Congress is considering a proposal to require background checks for sales at gun shows.

"One of my issues has been closing those loopholes," said Herrick, a McLean activist who serves on the board of directors of the McLean Community Center. "I am definitely a proponent of better regulation."

But while Foust doesn't focus on the issue, he's clearly not too far from Herrick when it comes to gun control.

"The only group that I will not take money from is the National Rifle Association," he said. "I just won't do that."

The two also hold similar stances on other issues.

Foust, a 47-year-old business lawyer, said voters are most concerned about growth, and he vows to do what he can to slow it down. He said sprawl has to be stopped, and he said the state legislature must give local officials more authority to do that.

"The reason I'm running is my concern about the trailers that are serving as classrooms," Foust said, "and the sprawl that is enveloping Northern Virginia and the congestion that's crowding our highways."

Foust said he believes residents will vote for him because he's focused on the growth debate.

"I don't perceive that she is as focused on the funding for education to get rid of trailers," he said of Herrick.

But listen to what Herrick has to say about that issue.

"Growth is going to be a big issue in all of the campaigns in Northern Virginia," she said, adding that the debate over development at Evans Farm has catalyzed the community. "People are beginning to realize the price they are paying for growth."

Herrick, too, promises to "try and give local authorities better regulation. . . . Their hands are tied a little bit."

And both candidates are trying to focus beyond the June primary, to the fall campaign against Callahan, a 32-year veteran of the House of Delegates.

Herrick and Foust both say Callahan is vulnerable now. They say his time representing the district, which stretches from the Arlington County line to the Loudoun County line along the Potomac River, is over.

The chairman of the House Appropriations Committee, Callahan is particularly vulnerable on abortion and public financing of a baseball stadium, they said.

"Callahan is the leading advocate for public financing of a baseball stadium," Foust said. "I am absolutely opposed to that."

Meanwhile, Herrick predicts that Democrats can attack Callahan for becoming more conservative and supporting Gov. James S. Gilmore III (R) more often.

"He's really going to have to show his Republican credentials," she said. "People are going to sit back and reconsider."

Herrick said she's confident that she will be chosen by voters to challenge Callahan, as she did unsuccessfully two years ago. As a civic activist and a former president of the McLean Historical Society, Herrick said she has a leg up.

"I haven't even thought about not winning," she said.

But Foust is confident, too. A newcomer to politics, Foust said he has the advantage because he's talking more about what people want to hear.

"I am very optimistic," he said. "I am advancing the cause of what people want to see done in this region, and as a result, they will support me."

The voters will decide who's right on Tuesday.

CAPTION: Carole Herrick is making second run.

CAPTION: John Foust is political newcomer.