For many long years, M. Jean Speicher, a candidate for the Maryland House of Delegates in the 21st Legislative District, has had the thankless task of being a Republican in Prince George's County.

She has watched, year after year, as the Democrats' registration advantage in the district stretching through College Park, Beltsville and Laurel has increased to 3-2, then 2-1, then to almost 25 to 1. And she has seen her long involvement in her Laurel neighborhood and the Republican Party do her little good in a 1974 campaign for the Prince George's County Council against a solidly backed Democrat, Frank Casula.

Now she is running for a delegate's seat and, knowing that no Republican has won a legislative race in Prince George's since 1960, she has had to campaign against three hard-working Democrats who have already gained considerable attention by winning a remarkably close primary.

It is a bleak prospect. Speicher says, however, that she has a real chance, this time, of "really surprising some people and winning." This is the year, she says, when voters-influenced by dissatisfaction with politicians and a new scene of fiscal conservatism-will finally decide to vote out some of the Democrats.

Speicher theory is not unusual; it is being broadcast loudly by every Republican candidate in the county. If the dreams of county Republicans are really to come true in this year's legislative election, they are as likely to be realized in Speicher as in any one else.

"She is certainly a good candidate," says Del. KayBienen, Specicher's neighbor, friend and one of her opponents. "She's competent and she's well known in the Laurel area. No one can afford to take her lightly."

In most of the other districts in Prince George's County, no combination of work and qualifications would be likely to enable Speicher and fellow Republicans Thomas Kennedy, Christopher Connoly, and Senate candidate Julia Brown to overcome the well-financed, still-powerful Democratic organization.

But the 21st District is different. Both Democrats and Republicans in the largely white, middle-class area agree that their voters are more likely to support individual candidates over parties, platforms or slates.

Republicans have other advantages as well in the 21st. GOP registration in the district has remained at 30 percent of party registered voters-compared to a county wide average of 24 percent, - and the district has often supported Republicans over Democrats in top-of-the-ticket races.

"There are a lot of government workers in the district who are Republicans, but who just don't vote in local races," sats Leonard Colodny, who lost to incumbant Sen. Arthur Dorman in the Democratic primary. "If they were to all turn out to vote for the executive's race, we could have problems."

Speicher says she is hoping, indeed, that Republican Larry Hogan's strong challenge to County Executive Winfield Kelly Jr. will help her considerably in a district where Kelly has never been popular. And she thinks that the hard-fought Democratic House of Delegates primary in the 21st-which saw Bienen, incumbant Pauline Menes, and Timothy Maloney nominated from a field of 10 by razor-thin margins-may have weakened the local Democratic organization.

On both counts, she has reason for hope. All fo the Democratic candidates in the 21st admit to being worried, at least, about Kelly's image and the possible tug of Hogan's coattails. Maloney, one of severl Democratic "outsiders" who was nominated without the endorsement of the Kelly-led party organization, says he will not endorse Kelly "unless he commits himself to some changes in the way this county and the Democratic Party operate."

Meanwhile, though all three Democratic delegate candidates and senate incumbant Dorman say that their party is now united and no division remains from the primary, it seems that the Democratic candidates will have to find most of their votes on their own.

"I don't think the healing process has really taken hold," said Colodny. "Most of us who were on the losing side in the primary as independents are out working now for Harry Hughes. Support for the district candidates has been left up in the air."

Maloney and Dorman are considered by most observers to be too well-based to be affected by potential Democratic weakness, however. Maloney, 22, has been highly active and visible in the district since the age of 11, has a large campaign organization, and as in independent Democrat, is largely immune to the Republicans' anti-machine rhetoric.

Dorman, who beat Colodny by a better than 2-1 margin in the primary, expects that his 14 years of experience in Annapolis as a delegate and senator will be enough to carry him past Julia Brown, a conservative Republican who finished fifth in the 1974 House of Delegates race in the 21st.

Republicans Speicher and Kennedy, in fact, have focused their campaigns to a certain degree on the records of Bienen and Menes. Kennedy, the current president of the county Young Republicans, accuses the two Democratic incumbants of being too quick to vote for increased spending and sales taxes. Speicher says they have not acted decisively to reform the Washington Suburban Sanitary Commission, an important issue in the district.

Both Bienen and Menes, however, stress their concern over the lack of regulation and organization in the WSSC and say they will continue to work towards improving it.