Peter Francis O'Malley wants to be governor. He says so; his friends say so. Even his political enemies realize it.

The trouble is, O'Malley concedes, most people outside the county's tight political circle don't know much about him, other than the fact that he is a millionaire corporate lawyer whose Democratic political organization once ran Prince George's County politics.

At a political fund-raiser last month, O'Malley worked the crowd as vigorously as any politician in the midst of an earnest campaign. He received an award from Democratic state Sen. Decatur Trotter of the state legislative black caucus, and an endorsement from his friend U.S. Rep. Steny Hoyer. Hoyer enthusiastically told the crowd that O'Malley would be the best governor Maryland ever had.

But much of the crowd, including several of the black legislators who said they never were consulted on the award, simply stared politely. They gave none of the applause that usually greets such a comment, partly because not everyone was sure what Hoyer was talking about.

O'Malley, 46, has couched his 1986 ambitions in the caveat that he will run if Baltimore Mayor William Donald Schaefer doesn't. That is a big if. Democratic Party politicians who have talked with Schaefer say it is almost certain that the mayor will run.

Yet the mere mention of O'Malley's interest has stirred up considerable speculation in a county where rumor can become fact overnight. Some politicians who have a healthy respect for O'Malley's influence have withheld endorsements for the other all-but-announced Democratic candidates: Attorney General Stephen H. Sachs, House Speaker Benjamin L. Cardin and Schaefer. Others have taken O'Malley's ponderings as a sign that O'Malley's old organization is reviving, and they wonder what that could mean to the changing face of Prince George's County politics.

O'Malley, who runs one of the largest law firms in Maryland, has carved out a new reputation for himself in recent years as an educator, a sports franchise entrepreneur and a well-heeled businessman. But in Prince George's County, he still is known primarily for the influence he wielded during the 1970s, when he and allies such as Hoyer ran Prince George's County politics.

His specialty then was getting other people elected, assembling candidate slates and merging the county's disparate Democratic factions into a single weighty organization that his critics called a machine. His organization backed nearly every successful candidate for office in Prince George's County during the 1970s.

O'Malley himself has been out of the limelight for several years, and even in his organization's heyday he never ran for a major office.

"I'm largely unknown," O'Malley conceded in an interview. The question now, he said, is, "How do I go about getting known?"

O'Malley dropped out of visible politicking in the late 1970s, after his friend Hoyer lost a bid for lieutenant governor. But Thomas Farrington, O'Malley's former law partner, said that O'Malley never was very far from the fray.

"Peter never stays out of anything," Farrington said recently. "He's on the phone. They call him. He was a tireless politician."

O'Malley said he has always wanted to run for public office but decided to wait until his five children were grown and he was financially independent.

Talk of Schaefer's involvement gives O'Malley great reason to pause. Prince George's Democratic politicians, ranging from O'Malley loyalist Sen. Thomas V. Mike Miller Jr. to County Executive Parris Glendening, have said they would like to support Schaefer for governor.

O'Malley himself hosted a reception for Schaefer at the Capital Centre in March and invited a group of local business leaders there to meet the mayor.

"I didn't introduce him to people as a courtesy to him," O'Malley recalled later. "I wanted him to accelerate his decision."

"If Schaefer runs, it will be difficult to draw attention to the differences between us that I would need to win," O'Malley said. "Unless you are one of the principal alternatives, it is difficult to be heard."

O'Malley envisions himself instead as an alternative to Attorney General Sachs, who O'Malley feels is representative of the liberal arm of the Democratic Party that voters rejected in last November's election.

"I'm a coalition builder," O'Malley said. "He's a lone wolf. I'm a patient reasoner. Steve is a confrontationalist."

Both O'Malley's and Sachs' forces agree that a contest between the two could widen rifts among Prince George's County Democrats. This was illustrated recently when Secretary of State Lorraine Sheehan, a Prince George's Democrat who split with O'Malley's organization some years ago, called a news conference to endorse Sachs.

"Traditionally, the organization has had a ticket from top to bottom in the county," said Joel Rozner, an attorney and political organizer who is one of Sachs' three Prince George's campaign chairmen. "I think most agree that Steve will not be at the top of the organization's ticket this year."

Gerard Devlin, a state delegate who is O'Malley's personal and political friend, believes that O'Malley's pull will prove to be stronger than Sachs' organizers anticipate.

"You'll see most of the political community in the county united behind whatever side O'Malley is on," Devlin predicted. "Sachs will be left with dissidents."

More than 250 of those Sachs supporters appeared at a Prince George's Community College fund-raiser on May 21 to demonstrate their commitment to the attorney general's aggressive gubernatorial campaign.

But several County Council members whose names appeared on stationery touting the rally have pulled back from Sachs' effort since the O'Malley rumors started flying. Only two, Anthony Cicoria and Richard J. Castaldi, have said that they are certain to endorse Sachs.

Castaldi said that other members played down their commitment because "the state senators put the heat on," an allegation Miller does not deny.

O'Malley's friends cite his business experience, as well as his political savvy, as reasons he would make a good governor. For three years, he served as president of the Washington Capitals hockey team. His Largo law firm has grown from six to 32 lawyers since 1974. He has been the chairman of the University of Maryland's Board of Regents, a trustee for his alma mater, Mount St. Mary's College in Emmitsburg, Md., and a member of several corporate boards.

O'Malley said his training enables him to know what it takes to attract jobs and businesses to Maryland, largely through building on the state's academic base.

"The industries that we are used to dealing with are disappearing," he said. "Business will locate where there is a trained work place."

Here the similarities between O'Malley and Schaefer begin. Schaefer has gained a reputation in Baltimore as a chief executive who has gone to great lengths to attract new types of businesses to a city whose old industrial base has been wearing down.

Before O'Malley can gauge his strength statewide, he will have to deal with the altered political climate in this county that his organization once dominated with ease. Once again, there are several warring Democratic factions at work in Prince George's, including a group of newly active black politicians and activists affiliated with the Maryland Rainbow Coalition. Such organizations draw their strength from a black population in the county that has grown to more than 37 percent.

Bennie Thayer, the Rainbow Coalition's leader, said he is wary of O'Malley. Thayer has hinted repeatedly that he would like to challenge O'Malley's friend Hoyer for his congressional seat in 1986.

"Pete O'Malley would have to do an awful lot toward persuading me to support him ," Thayer said.

O'Malley said he will not pursue what he calls racial politics.

"One doesn't change principles because demographics change," he said. "If it is different to not pursue the racial and ethnic vote as a separate entity, then I'm different."

Some county politicians say O'Malley has told them that if Schaefer runs, O'Malley would like to be lieutenant governor or attorney general. O'Malley insists that he has no such secondary motive.

And some who know him don't doubt that he wants to shoot for the top. O'Malley, Devlin says, is a "frustrated monsignor. I think Peter would become a priest if he could start out as an archbishop."