Michael and Claudia Schreiber, 30-year-olds who moved with their two children to German-town last year, are typical of a new breed of voters populating upper Montgomery County: young, professional, family-oriented and conservative.

They are registered Republicans -- mainly, Claudia Schreiber said, because "the current administration has been good to us."

Although the Democratic Party has traditionally held sway in Montgomery County, that is changing in District 15, where the Schreibers live and where the gap in party registration has narrowed significantly.

In the past four years in that area -- which stretches from wealthy Potomac to the growing middle-class communities of Germantown, Gaithersburg and Damascus -- party registration has shifted from 51 percent Democratic and 35 percent Republican to 48 percent Democratic and 37 percent Republican.

Countywide, 55 percent of registered voters are Democrats, 30 percent are Republicans and 13 percent are independents.

The increase in Republican registration in District 15 is expected to play an important role in the elections this year. Five Democrats, two of them incumbents, and four Republicans are vying for three District 15 seats in the Maryland House of Delegates in the upcoming primary.

Some observers predict that, in particular, the change in voter patterns may lead to a close race in the general election for the seat vacated this year by Del. Jerry Hyatt, Republican Party registration in the district has risen from 35% to 37%. a race they say is shaping up between Democrat Sandra Bregman and Republican Jean Roesser, both of Potomac.

The top three vote getters from each party in the September primary will run in November's general election. The delegate seats will go to the three with the most votes in November.

Political observers are giving the edge for two seats to the Democratic incumbents: Gene Counihan, a 45-year-old public school administrator from Gaithersburg, and Judith Toth, a 48-year-old health care consultant from Germantown, who were strong vote getters in the 1982 election.

Also running in the Democratic primary are Miles Alban, 44, a Montgomery County police detective from Damascus, and Ron Wohl, 43, a businessman who lives in Gaithersburg.

Others running in the Republican primary are Ronald Bird, 42, a county police officer who lives in Damascus; George Fetter, 38, a systems analyst from Gaithersburg, and Christopher Fiotes, 53, a federal government worker who lives in Gaithersburg.

The general election race for the third delegate seat may turn out to be between Bregman, a 48-year-old political activist from Potomac with a background in public relations, and Roesser, a 56-year-old reporter for the Suburban Record who also lives in Potomac, observers said.

Both women have sought funds aggressively and are campaigning door to door.

Bregman is on the Democratic slate with Counihan and Toth, an advantage in that the candidates will pool their resources for fundraising and advertising.

Roesser ran for delegate in 1982 and came in fourth behind Hyatt in the general election.

"I think Jean Roesser is a candidate who has to be taken seriously," Counihan said.

Alan Levey, the state GOP chairman, said the increase in Republican voters and the fact that Hyatt is not running again will greatly improve Roesser's chances of winning.

Bregman predicted that it will be a close election, but one that she'll win, in part because of her slate affiliation.

Roesser, on the other hand, said her "chances of winning are better than ever" because, with an eye toward November, she is addressing her campaign to voters of both parties. "There are a lot of sympathetic Democrats," she said.

Roesser and Bregman said they are interested in many of the same issues, including increased funding for schools and roads, more day care in the upcounty area and better salaries for teachers. But differences of opinion on issues such as abortion, gun control, federal funding to expand the Metro system and federal deficit reduction legislation are likely to surface if the two candidates confront each other in debate.

Bregman said she would like to debate Roesser, but Roesser said she will participate in a debate only if it includes all the candidates.

"If Roesser adheres to the Republican party line there will be differences of opinion between us," Bregman said