Will Campos, a special assistant to Prince George's County Executive Jack B. Johnson, won the Democratic nomination to succeed former County Council member Peter A. Shapiro (D-Brentwood), based on unofficial returns from the county Board of Elections late last night.

Campos, a political newcomer, received 1,306 votes, nearly a third of the 3,991 Democratic ballots cast in the race for the District 2 seat.

He will face Republican Tommy S. Priestley in November.

Voters turned out in higher numbers than anticipated, election officials said. In previous special elections, about 10 to 13 percent of registered voters went to the polls. Yesterday, nearly 19 percent of the 22,246 registered voters in District 2 cast ballots.

Campos, celebrating his victory at CocoCabana, a Langley Park restaurant, credited his success to the work of an "unbelievable team."

"We built a team, literally an army, and from Day One we pounded the pavement and delivered my message about enhancing Prince George's County, and I think the voters appreciated that," he said.

Campos picked up early support from Rep. Albert R. Wynn (D-Md.), Del. Justin D. Ross (D-Prince George's) and Del. Victor R. Ramirez (D-Prince George's). Wynn provided Campos with manpower, money and a campaign manager.

District 2 is an ethnically and racially diverse area made up of communities along the D.C. border, including Hyattsville, Mount Rainier, Langley Park and Brentwood.

Trailing Campos was Karren Pope-Onwukwe, a lawyer and official with the Prince George's Central Democratic Committee, who collected 830 votes. Malinda Miles, a consultant and member of the Mount Rainier City Council, was third with 680 votes.

The other candidates were Chris Currie, a product development manager and member of the Hyattsville council; Derrick M. Posey, a teacher; Amber Waller, a member of the Prince George's Democratic Central Committee; Jennifer Mitchum, a substitute teacher; and Anthony J. Cicoria, a two-term County Council member who went to prison in 1990 for misusing campaign funds.

The Board of Elections had technical difficulties last night compiling results. Election workers said the main modem to receive results from the polls had malfunctioned.

Election officials said there were no major problems at polls throughout the day.

The only known glitch was at Mount Rainier Elementary School. When polls opened yesterday, nearly a dozen voters were told the machines were not pulling up the Democratic slate.

Linda Couch, a Mount Rainier resident, said poll workers told the voters that because the machines weren't operating properly, they could write down their choice on a piece of paper. Couch said some voters left, saying they would try to come back. Others, like her, wrote their selections down on the paper.

Shapiro decided to accept a position at the University of Maryland and give up his council seat midway through his second term.

Will Campos, a special assistant to the county executive, credited the work of an "unbelievable team" for his success.