U.S. Rep. Steny H. Hoyer, Prince George's County Executive Parris N. Glendening and Maryland Gov. William Donald Schaefer are spending $15,000 each on radio ads broadcast this weekend in which they endorse Prince George's State's Attorney Alex Williams.

Glendening said the advertisement for the first-term prosecutor is "insurance" for a victory most political observers concede probably is inevitable.

But why the special effort?

Although he is widely perceived as the front-runner over Republican Arthur A. "Bud" Marshall, Williams is not taking the race for granted, and neither are his party boosters, lest the first black prosecutor in the county's history be upset or win by a less-than-resounding margin.

Either of those outcomes, most observers say, could have serious political consequences in the county of 720,000, where blacks are becoming a majority and white leaders are working to "share power" without losing it.

Some of the rhetoric surrounding the race is strong. If Marshall wins, state Sen. Albert R. Wynn (D-Prince George's) said in an interview, "it would have a truly polarizing effect on the county and would open the door to true race politics . . . . It would be Armageddon."

Hoyer, speaking recently at a political gathering at Prince George's Community College, said the "way to respond to those who represent hate and racism" is to "go into the voting booth and pull the Alex Williams lever."

Marshall, who held the post for 24 years before losing to Williams in 1986, scoffs at any suggestion that his election would be racially polarizing. "In my living room, we created the first integrated {political} club in Prince George's County, the Lanham-Bowie Democratic Club," he said. He also cited his efforts with former assistant state's attorney and now retired Circuit Court judge James Taylor to integrate restaurants in southern Prince George's that wouldn't serve blacks.

Key to the outcome, Wynn said, will be the black voter turnout for Williams and the number of white Democrats crossing party lines to vote for Marshall, a former Democrat who turned Republican this year.

Despite such talk, neither candidate is making race an issue. And Williams is quick to acknowledge that Marshall is no bigot.

"I have some black support," said Marshall. "I would have to say it's sort of minimal. I would like it to be more."

Williams attributes Marshall's support not to race, but to his long tenure as the state's attorney. These are "the party people he's grown with over the years," Williams said. "That's his strength. I can't do anything about that."

State Senate President Thomas V. Mike Miller Jr., who represents the 27th legislative district in southern Prince George's, said he believes Marshall could win, "but he would really need strong resources {that} the national and state {Republican} party is unwilling to commit and the local party doesn't have."

"It will be closer than any other race, but Alex will prevail," he said.

A month-old poll done for the Williams campaign showed the Democrat leading in all of the county's eight legislative districts.

Williams was weakest in the 23rd, encompassing Bowie and Greenbelt, and the 27th.

In both districts, 50 percent favored Williams, 30 percent Marshall and 20 percent were undecided.

A more recent poll of 300 voters in the 23rd, done for the Democratic legislators there, showed Williams leading Marshall by 38 percent to 36 percent, with the rest undecided.

The support Williams has from party regulars reflects a smoothing over of differences that arose when Williams contributed money to the primary campaigns of candidates running against the Democratic slate.

"I was a bit piqued," said state Sen. Thomas Patrick O'Reilly, who has since jumped on the Williams bandwagon. "Bud Marshall was an institution in years gone by and obviously he has friends and name recognition that would be tough for anyone to overcome," said O'Reilly. "But I really believe we're going to win. The only question is whether we're going to win by a large or a small margin." Staff writer Richard Tapscott contributed to this report.