Maryland House of Delegates candidate John d'Eustachio says he is discouraged about the way Democratic politics has worked this primary season in the 21st District of Prince George's County. But he says he is not resigned.

A former district coordinator for State Sen. Arthur Dorman, d'Eustachio was passed over by Dorman when a slate of four Democratic State House candidates headed by Dorman was assembled for the September primary.

The slate, which includes incumbent delegates Timothy F. Maloney and Pauline H. Menes, picked up College Park businessman James Rosapepe instead of d'Eustachio, who was thought by some political observers to be a certain choice because of his work for Dorman. There are three House seats from the 21st District, so the slate choice left d'Eustachio and candidate Claire R. Bigelow to fend for themselves.

Dorman said the choice of Rosapepe was made to "round out the ticket" because of Rosapepe's experience in business. "John was my original choice, but the feeling by all of us was that Jim was better suited to what we were looking for," Dorman said. "I hope there isn't any bitterness, but in this process, these things happen."

D'Eustachio, however, said he was hurt by Dorman's sudden change of heart. "I worked with the man for three and a half years, and it was just assumed I was going to run with him," he said.

Nomination to the party slate in the predominantly Democratic district -- where no Republicans are registered to run -- gives a candidate a greater likelihood of victory. Being on the slate allows greater visibility and, more importantly, allows candidates to pool resources.

D'Eustachio said being left off the ticket made him even more determined to win.

The fallout from the political process promises to make for a lively race in the 36,000-resident district. The candidates agree that it will be difficult to predict the outcome because both d'Eustachio and Bigelow are well known in the area. District 21 includes College Park, Beltsville, University Park, Langley Park, Adelphi, Berwyn Heights, and parts of Calverton, Chillum and Takoma Park.

It is home to University of Maryland students and government workers, working class and upper-middle class, and has black, Hispanic and Asian neighborhoods. There are 22,859 registered Democrats and only 9,452 Republicans, making the area a longtime Democratic stronghold.

Dorman, 59, is a three-term state senator who is vice chairman of the Senate's Economic and Environmental Affairs Committee.

Maloney, 30, is a two-term incumbent who serves on the House Appropriations Committee and chairs the subcommittee on corrections and transportation. His colleague, Menes, 62, has served since 1966 in the House of Delegates and sits on the Judiciary and Rules committees.

Rosapepe, 35, is a partner in three ventures -- a public policy consulting firm, an investment banking firm and a survey research and public relations company. He is a member of the Democratic State Central Committee and treasurer of the Maryland Democratic Committee.

D'Eustachio, 42, an administrator at Suitland Senior High School, lost a primary bid for the House of Delegates by 10 votes four years ago to Thomas J. Mooney. From 1978 to 1983 he served as chairman of the county Human Relations Committee, which hears discrimination complaints.

Bigelow, 58, has a background in social services and helped establish a county rape crisis center. She was a founding member and past president of the county Women's Political Caucus, was president of the county American Civil Liberties Union chapter and was a delegate to the 1976 Democratic National Convention.

Dorman is running unopposed.

Twelve Democrats ran for the three seats in the last House election in 1982. Both Dorman and Menes, who ran on a slate with d'Eustachio, won in that election.

"It's hard to beat the slate in any district in the county, but if you expend a tremendous amount of energy it can be done," said Del. Thomas J. Mooney, a former Democrat from District 21 who changed parties and is giving up his seat to run as the Republican candidate for governor.

Members of the District 21 slate are not united in their choice for the top job in Maryland: Dorman is leaning toward Baltimore Mayor William Donald Schaefer for governor, but Menes and Maloney are supporters of Attorney General Stephen H. Sachs. Rosapepe would not say who he was backing.

Challengers d'Eustachio and Bigelow say they hope voters will respond to their independent campaigns, as residents there have been known to do in the past.

The district includes part of Konterra, a planned "mini-city" near Laurel that advocates hope will pour money into the region and that critics charge will strain roads and create serious traffic problems.

"There's a concern about roads already being overburdened," Rosapepe said. "Although Konterra hasn't even been built, there's a lot of recent growth in the area."

Members of the slate who are currently in the legislature point to recent road repair projects in College Park and along New Hampshire Avenue as proof they are addressing the problem, but d'Eustachio maintains that the district "does not seem to get a lot of repair work, and I don't know why."

In addition, the University of Maryland also brings its own concerns to the region. A continuing problem, Maloney said, is the lack of on-campus housing for students, many of whom must look in the suburbs for housing. The presence of group homes, however, can threaten property values, he said.

In addition, "Crime and drugs are very much on everyone's mind," Menes said. "Residents have almost pleaded those of us in the General Assembly to do anything we can to protect them."

Bigelow said she believes some of the concerns voiced by residents are falling on deaf ears. "Some of the legislators have been in there a little too long," she said.