Even as supporters of Prince George's State Sen. Tommie Broadwater Jr. angrily criticized his conviction yesterday, some political activists had begun to prepare for a major reshaping of political power in the county's growing black community that may have lost its most charismatic leader.

Democratic Central Committee Chairman Gary Alexander, whose committee will be charged with selecting an interim replacement for Broadwater, said party workers and officials began calling him as soon as they heard Broadwater had been convicted of food stamp fraud, wondering what procedures would be used to fill the seat.

Maryland law requires that Broadwater be replaced by an interim senator upon his sentencing. If the conviction is upheld upon appeal, the central committee must choose a permanent replacement.

The prospect of replacing Broadwater, the county's only black state senator and a major influence in county politics, prompted many black officials and activists to express publicly the alarm many of them have felt privately since his arrest.

"It's going to be hell, really, to try to determine who's going to fill that seat," said County Council Vice Chairman Floyd Wilson, one of the county's senior black officials. "He's the top black official in the county, and we all look to him for leadership."

Several black community leaders agreed Broadwater's absence from the political scene could stall the black community's efforts to expand its influence. While the county's population is close to 40 percent black, only two of nine council members are black and six of the 30 state legislators.

"I think it could have dire implications for the emergence of black folks in Prince George's County as a political force," said Wayne Curry, a prominent young county lawyer who has himself been mentioned as possible successor.

Curry said he is not a candidate and said he believed no lobbying for the seat had yet occurred.

But other political insiders said that as testimony in the case was given over the last few days, numerous political figures quietly indicated their interest in the seat or their support for others.

Among those who have been named as possible successors are school board member Bonnie Johns; Orphans Court Judge Decatur Trotter, who made an unsuccessful run against Broadwater in 1978; Wilson; and citizen activist Cora Rice.

Wilson, in line to become the council's first black chairman, said yesterday he was not a candidate.

Also frequently mentioned were each of the delegates from Broadwater's 24th legislative district: Nathaniel Exum, Frank Santangelo and Sylvania Woods Jr. Woods' father, District Court Judge Sylvania Woods Sr., also has been suggested. All but Santangelo are black.

Appointing one of the delegates from within the district could be a problem, however, because each of them has been criticized in the past for alleged conflicts of interest. Said one legislator who asked not to be named, " The central committee will be looking for someone clean as, say, Caesar's wife."

Key to Broadwater's ascent from obscurity, beginning in 1974 with his Democratic machine-backed election to the Senate, was the loyalty he inspired from the inner-beltway community of Fairmount Heights in which he was raised. That loyalty was much in evidence yesterday, as customers of Broadwater's businesses continued to insist he was innocent.

At the Ebony Inn Restaurant on Sheriff Road, where Broadwater rose from a meat cutter to coowner, customer Dorothy Crawford said Broadwater had been "railroaded, set up, all of it."

"I don't know too much about politics, but I think he was just too powerful. They wanted that seat," Crawford said. Across the street, at the supermarket Broadwater owns, a customer shrieked as the news of the conviction came over the radio.

"I was cleaning fish," said store clerk Posie Turner. "I heard somebody scream, 'What!' Everybody just kind of listened. No one said anything. They just went back to what they were doing. I don't believe it."

Washington Post staff writer Margaret Shapiro also contributed to this story. graphics/map: MARYLAND STATE LEGISLATIVE DISTRICT 24 TWP