The rumor first surfaced last fall when Prince George's County Democrats were squabbling over an appointment to the county council and one Peter F. O'Malley briefly emerged as a bit player. It was fed when the Democratics were fighting over the leadership of the county delegation in Annapolis -- and again O'Malley was involved.

Like any hot political rumor, it hung out there for weeks in the county's Democratic circles, an object of scrutiny, speculation, desire and concern before surfacing two weeks ago as fact: Peter Francis O'Malley, the powerful Democratic Party strategist who had gone into political exile several years ago out of frustration at being called a "boss," was getting back into politics.

For the last two weeks, O'Malley has been politicking just as he did before: coaxing, wheedling, charming, subtly calling in chits, going back to politicians whose careers he fostered through a decade of slate-making, all in order to win his first political battle in nearly three years, the congressional race of his best friend and political alter ego, Steny Hoyer.

But while the techniques are the same as they always have been, there is a decided and carefully cultivated difference. Once almost explosively defensive about any suggestion that he had created and run a suburban political "machine," O'Malley now says he was "unduly sensitive." Once insistent that he had no more political clout than anyone else in the party, he is now willing to admit that he played -- at least -- an unusual role.

"I have arrived at a sufficient degree of maturity that I don't take [the criticism] personally," he says. "There has never been a race where one faction has not tried to place the label of machine or bossism on another faction. It's an acceptable price to pay. I don't think it's an accurate characterization."

Said Prince George's County Council Chairman Parris Glendening, who has kept contact with O'Malley during his three-year absence from active politics: "He has made it pretty clear that one of the mistakes of the past was trying to deny or shy away.He's ready to be much more open in the way the system ought to work. He's saying he's ready to be out on the front page of The Washington Post." Said another friend in the party: "Peter's tired of apologizing for himself. He's going to be out front this time."

This is astonishing stuff for the people and politicians who know Peter O'Malley for here is a man in past years drew painstaking color-coded charts to document that the party was simply an inclusive coalition, not a machine.

Here, too, is a man whose skittishness about publicity -- even in his other roles as lawyer, University of Maryland regent and, for a time, president of the Washington Capitals -- is as legendary as the political skills that enabled him and a couple of friends to put together a Democratic Party organization that eventually controlled every elected position in Prince George's.

The organization had its roots in a 1966 state senate campaign run by O'Malley, then a 27-year-old lawyer. Within a couple of years, O'Malley and his friends had hustled and cajoled their way into a position of power that allowed them to organize a county-wide slate of allies and incumbents. Those who were not willing to work with them and were beatable were purged.

When the slate swept every post from county executive to registrar of wills in the 1974 election, O'Malley and friends were well-established as the leaders of what was obviously the only game in town. They became the people to go to if you had political ambitions, wanted a state or county appointment, or had a problem.

"I don't know that you could say there was a capo di capi, but they decided who was going to be the judge and they decided patronage and they decided who was on the slate," said Del. Frank Pesci, who ran with the organization but was continually at odds with it. "It wasn't a corrupt thing. I don't think that's their bag. This was political power, influence."

But having put together an organization which nearly every politician in the state had to court and which rivaled any in Annapolis in terms of sheer clout, O'Malley began hearing complaints that he was too powerful. By mid-1978, he fled the world of daily politics altogether because he couldn't stand being called a boss. Says O'Malley: "It wasn't fun anymore."

Since O'Malley's withdrawal and the 1978 election defeats of Hoyer in the lieutenant governor's race and Winfield Kelly Jr. in the county executive race things have not been the same. Once unified and well-controlled, Prince George's Democrats are now split into frequently warring factions.

The extent to which the organization O'Malley helped run has come unhinged is most visible in the current race to fill Gladys Spellman's congressional seat. Where once Hoyer might have been given a clear primary field as the party's golden boy and leader, he is now simply one of 19 candidates.

The lack of structure in the party has produced decidely mixed feelings among Democratic officeholders, who since the 1978 election have been left to their own political devices. Those who came up through, flourished under and found security in the O'Malley organization now gripe that they and the party have lost power at home and at the statehouse in Annapolis. Others, including a handful who battled the organization to get into office, speak of new independent thinking among Democrats.

As a result, what might in any other place be an event of little interest -- the reemergence of an inactive but influential political figure -- has in this politics-obsessed county set the Democrats aflutter. As the news of O'Malley's decision to step back into politics for the Hoyer candidacy filtered into Annapolis and Upper Marlboro, there was, in the words of Del. Timothy Maloney, a friend but political adversary of O'Malley, "a nervous undercurrent. Nobody is quite sure what it is going to mean."

Those who had never gotten along that well with the organization have begun warning darkly of a return to the machine politics of the past. Some of Hoyer's congressional opponents, including Bowie Sen. Edward Conroy and Gladys Spellman's husband Reuben, who were part of the organization, have also picked up the charge as a potentially effective piece of campaign rhetoric.

But this time, O'Malley says, he is determined to remain untouched by it all. "I was sure when Steny decided to run we would see a repeat of what we've heard since 1962; that is the cries of machine politics," he says. "Either you stay out of it and let things happen or get back involved and deal with periodic annoyances. It's an acceptable price to pay."

Every day, O'Malley, now 42, spends hours at the Hoyer campaign headquarters or his nearby law office with a telephone receiver to his ear, marshalling the troops, checking campaign operations, making sure everything is just so. "I thought he would be a reluctant dragon, just getting into it for Steny," said Farrington. "But he's like a kid in a sandbox. He just loves it."