Every Sunday at a Catholic church in or around the heavily Democratic 18th Legislative District in Montgomery County, a group of teen-agers washes car windows and places on clean windshields campaign literature for Daniel Boyle, a Republican candidate for the House of Delegates and staunch opponent of abortion.

As far as anyone knows, abortion is not the issue in the 18th District, which encompasses Chevy Chase, Kensington and part of Silver Spring.

Even Boyle, a physician and one of three Republicans seeking to end the all-Democratic reign in the district, prefers to discuss reforms of the health care system, solutions to drug use among teen-agers and his support for cutting property taxes through the TRIM (Tax Relief in Montgomery) ballot referendum.

But as the former head of and chief lobbyist for Maryland Right to Life, Boyle acknowledges that most of his 150 volunteers have joined him because of his abortion position.

"Running as a Republican in my district is very difficult," he said, "and I thought if I had a chance of winning, it would be partly because of my abortion position."

Consequently, said an active Democrat, the role that abortion sentiment will play in the election "is an unknown factor in the equation."

Although the three Democratic House candidates oppose Boyle's anti-abortion position, they have an ace in the hole.

Margaret Schweinhaut, the incumbent state senator who heads the district's tightly knit Democratic slate, voted against Medicaid funding for abortion in the legislature.

This distinction highlights a key theme in the race.

"Our group is not monolithic," said Roy Dickinson, who is active in the entire Democratic effort. "Peggy says there are people with her on the slate who have differing points of view - and that the voters should look at their total output as a team.

"Combined, they represent a broad range of interest."

The Democratic House ticket includes Donald Robertson, a lawyer, a two-term incumbent and chairman of the county delegation to Annapolis for seven years; David Scull, a public interest lawyer, and Patricia Sher, an activist in the party ranks and a member of the Maryland Drug Abuse Commission since 1972.

Scull and Robertson have led fights for ethics legislation and election law reforms. Robertson has served on a committee studying the state tax structure and has worked for greater utility regulation. Scull has promoted stream-lining the legislative process, tenants' rights and has proposed "de-lawyering" legal procedures such as uncontested divorces and adoptions.

Schweinhaut, who after 23 years in Annapolis has achieved a leadership position in the Senate, has built a lengthy record from sponsoring legislation for nursing home patients' bills of rights to programs for the elderly, mandatory standards for protective car bumpers and the state public defender system.

In opposition stand four Republicans, who have been less inclined to run as a team. They are Donald Dalton, a lawyer, who is campaigning against Schweinhaut and three House candidates; John Dean, a Chevy Chase lawyer (who is no kin to the Watergate figure by the same name); Lorenza Simmons, vice president of a construction and interior design firm, and Boyle.

Dalton, who has attacked Schweinhaut as being out of touch with the citizens, said his own program is "short and sweet like the old lady's dance - I believe in low taxes, curtaining inflation, economy of energy and change in the old system of government at Annapolis."

Simmons, of American Indian heritage and an activist in women's causes, said she believes the social "separatism" that exists among various interest groups has perpetuated "government waste." She said she favors rent controls that are "not injustices to landowners" and she believes the county economy should expand.

Dean has campaigned against what he calls the traditional "big spender" role of Democrats in the legislature. "They've been big tax raisers and they've given us more government that we want, need or can afford," he said. He criticized the election year legislative rollback in assessements as a "political ploy" that produced no tax reductions in his neighborhood.