Mary H. Boergers quickly recited her name and purpose as commuters swirled past her at the Shady Grove Metro station.

"I'm running for the state Senate," she said repeatedly, smiling broadly and handing out black-and-white brochures.

Her counterpart, S. Frank Shore, was also out campaigning in Montgomery County last week, going door to door, distributing emery boards bearing his name and an admonition to vote Sept. 11.

In the summer of 1990, this is how the battle over abortion is being fought and how it will be decided in Maryland.

Boergers, a two-term member of the state House of Delegates, is an abortion-rights supporter. She is seeking to oust fellow Democrat Shore, a staunch abortion opponent, from the state Senate seat he has held since 1978.

Their Montgomery County district -- encompassing Rockville, Gaithersburg and Garrett Park -- is one of nearly a dozen in the state in which politicians believe voter attitudes toward abortion could tip the outcome of races and determine the makeup of the General Assembly.

Boergers, a 44-year-old former teacher, was one of three challengers for seats in the 47-member Senate to be targeted for maximum assistance by the Maryland chapter of the National Abortion Rights Action League. Much of the political action on the abortion question in the state centers on the Senate, after a filibuster last winter by 16 senators that tied up a bill guaranteeing continued access to abortion and led to a compromise that later died. Similar endorsements went to Del. Patricia R. Sher in her primary challenge to Sen. Margaret C. Schweinhaut (D-Montgomery) and to Del. Gloria Gary Lawlah, who is opposing Sen. Frank J. Komenda (D-Prince George's) in the primary.

Although Boergers and Shore say they would prefer it not be a single-issue race, their contradictory stands on abortion and similarities on other issues make it almost inevitable. State legislative races often are decided on personalities and connections, but abortion provides a clear and emotionally evocative difference in this case.

"This is a national campaign," said Shore, 54, a retired communications worker and 20-year legislator. "I feel like I need two bulletproof vests this year."

Boergers said she has come under attack from Maryland Right to Life. "If you're going to lose the fanatical Right to Life vote, you have got to have the pro-choice people with you," Boergers said. After the Supreme Court last year gave states latitude in regulating abortion, Boergers said, "we found . . . for the first time that there are more pro-choice, single-issue voters."

Shore was one of the antiabortion senators who filibustered for eight days in March to successfully stall an abortion-rights bill that had majority support. He is remembered largely for his clowning during the filibuster, wearing the same glen plaid suit throughout and waving a football around the Senate chamber while proclaiming his effort "the super bowl for life."

"It's such a heavy issue, I have to keep it lively to keep my sanity," Shore said. "It's my style. I'm not running a Rhodes Scholar campaign. I'm running a Frank Shore campaign."

Shore's folksy style has been good enough for the 17th District for two decades. With a base of support in the Elks, Moose and American Legion halls, he escaped primary opposition three times in the heavily Democratic district.

Although the district has changed less than others in fast-growing Montgomery County, several experts wonder whether Shore's style has gone out of style. "People have cable TV and VCRs," said one county political aide. "They don't hang out in the halls like they used to, and Frank hasn't built on his base."

Joseph M. Madden, a founder of the Rockville Elks Lodge and former American Legion commander, said he sees no erosion in Shore's support. As a delegate, Shore helped win passage of a law allowing service organizations to obtain liquor permits. "We remember that," Madden said.

But Robert Hollis, exalted ruler of the Elks lodge, said he knew of no clear favorite for the Senate among his members.

Despite being the incumbent, Shore lost out to Boergers on important endorsements from Democrats for the '90s, the AFL-CIO, the Montgomery County Education Association and the Fraternal Order of Police. He has, however, been endorsed by County Executive Sidney Kramer.

Ken P. Reichard, a Maryland AFL-CIO vice president, said abortion was not a factor in the union's endorsement. But, he added, "it's the hottest issue out here."

Mark Simon, president of the education association, said abortion was not an overt factor in the deliberations over which candidate to endorse. "I can't tell you what was in people's hearts," Simon added. Noting that three-fourths of the 6,600 members are women, he said, "There is a lot of support for Mary among our members."

Boergers, who said she has raised about $60,000 for the race, considered a run against Shore in 1986 but opted for another term in the House at the urging of then-County Executive Charles Gilchrist. This time, she began planning early, getting a discount by placing an order last fall to get her name and photograph on the back of Metro fare cards. The cards went into circulation at stations in her district this week.

"I've been telling everybody that if Frank Shore were pro-choice, I'd still be running against him this year," Boergers said. "I don't want to be perceived as a single-issue candidate, even one that important to me."

Shore, who estimates he has about $4,000 for the campaign, said he expects to be outspent 10 to 1. For now, he's trying to raise enough money to print leaflets. "How can a 20-year senator run a campaign without a brochure?" he asked.

The incumbent thought he got a break just before July 4. A radio spot he had prepared was broadcast several times on a conservative Silver Spring talk radio station, WNTR. The ad, featuring a fife and drum and calling for volunteers to "Shore's Crusade," was programmed into a computer and inadvertently aired before its schedule, Shore said. But a station spokesman said WNTR expects to be paid for some of the broadcasts, saying there was a "miscommunication" about when the spot was to run.

Given his lack of campaign funds and endorsements, along with polls in the district showing a majority favoring abortion rights, Shore is quick to portray himself as a decided underdog.

"I'm like Houdini in a box, wrapped up in chains in a box in the Detroit River," Shore said. "Will he be able to get out? Somebody get the keys."