Prince George's voters overwhelmingly reelected County Executive Parris N. Glendening (D) to an unprecedented third term yesterday, and State's Attorney Alex Williams (D) decisively defeated his predecessor, Arthur A. "Bud" Marshall Jr. (R), who was seeking to regain the job he had held for 24 years.

In the 2nd County Council District, Stephen J. Del Giudice claimed victory in his last-minute write-in campaign for the seat held by fellow Democrat Anthony J. Cicoria, convicted last week on theft and income tax charges. But Democrat Tommie Broadwater Jr., seeking to make a political comeback after his 1983 conviction for food stamp fraud, appeared to lose his write-in bid to retake the state Senate seat held by his successor, Decatur W. Trotter (D).

A victory by Del Giudice would be the first successful write-in campaign in state history for a county or state office.

Glendening beat Republican Charles W. Sherren Jr. by a ratio of nearly 4 to 1, a majority the county executive hailed as "a mandate for the direction of Prince George's County. It shows that people are pleased with the level of services in the county, that they're happy with the leadership in this county."

Williams beat Marshall by a ratio of 3 to 2, in a contest that was widely regarded as posing the stiffest competition facing the Democrats, who have three times as many registered voters as the GOP in the county.

"I'm pleased, proud and quite happy," Williams said at the Democratic victory celebration at a hotel in New Carrollton.

"I am very pleased by the turnout. We showed strong support all over the county. I certainly think this shows that the citizens are pleased with the job we have done."

The final outcome of the two write-in campaigns awaited an official count scheduled for Saturday. But based on the total number of votes cast in the districts and the votes cast for candidates on the ballot, it appeared that Trotter had defeated Broadwater, and Del Giudice felt confident enough to declare "an overwhelming victory."

In other contests, Democrats swept the County Council and won in all legislative districts, except for District 13B, which includes parts of Laurel in Prince George's and lower Howard County. There, incumbent Democrats William Beavan and Robert De Pietro were defeated by Republicans Martin Madden and John Morgan.

In school board races, Verna Teasdale defeated Kenneth E. Johnson and Frederick Hutchinson beat James M. Davis. Incumbent Suzanne M. Plogman was unopposed in her bid to retain her school board seat.

In ballot questions, voters passed a charter amendment calling for a special election if a vacancy occurs during the first two years of a four-year council term. They also authorized officials to borrow $111 million for public works projects, including schools, libraries and roads.

The Republican Party failed to field a full slate of candidates, despite a recruiting effort. Democrats in two County Council races and three state Senate races had no Republican opposition.

About 48 percent of the county's 263,164 registered voters cast ballots, slightly more than during the primary. The percentage reached 50 percent in the 2nd County Council District, where 12,186 turned out but only 1,758 voted for Cicoria and 1,032 for Ball, suggesting a large write-in for Del Giudice.

The GOP disavowed its candidate, J. Lee Ball Jr., in Cicoria's council district, which includes Hyattsville, Mount Rainier and University Park. Republican Chairman Richmond Davis had urged residents to vote for Cicoria, who faces suspension from office upon his Dec. 12 sentencing, to force a special election.

Cicoria announced on Friday that he was quitting the race and joining party leaders in backing Del Giudice. But it was too late to remove his name from the ballot. Workers for Del Giudice, the mayor of Takoma Park, distributed name stamps, 15,600 pencils and instructions on how to write in his name at polling places.

Staff writer Michele L. Norris contributed to this report.