A group of Prince George's County Democrats, following the lead of other Democratic groups around the state, has begun organizing support for a possible presidential campaign by Sen. Edward M. Kennedy (D-Mass.).

An organizational meeting that attracted about 75 Democrats last week in Largo was called by County Councilmember Gerard T. McDonough and state Del. Charles T. Ryan Jr. of Bowie.

So far, the group has won the support of three other County Council members -- Floyd Wilson, Deborah Marshall and Ann Lombardi -- as well as state Sen. Arthur Dorman and three other delegates to the General Assembly.

Although the Kennedy campaign is still hypothetical, the Kennedy supporters are the first Prince George's political leaders to begin work on a 1980 presidential campaign.

"It's a very ad hoc group right now," McDonough said in an interview, "The idea now is to set up meetings in each state senatorial district to recruit people, then try to have a large, countywide meeting where we can really draw a crowd."

McDonough said he had talked to other Kennedy supporters attempting to put together a statewide organization supporting the Massachusetts Democrat's candidacy, but that the Prince George's group was not officially tied to them.

"Traditionally, the Kennedy group will send their own people in to run a campaign," McDonough said. "Our idea is to give them the advantage of having a precinct organization already set up, so they can come in and get started right away when they're ready."

McDonough said he expected that both President Carter and Gov. Edmund G. Brown Jr. of California would be supported by groups of Prince George's Democrats. But he predicted that a Kennedy candidacy would have the backbone of the Democratic organication that has dominated county politics in recent years.

His contention is supported, in part, by the early support of Dorman, one of the leaders of Brown's successful campaign in Prince George's in 1972. "I don't like a lot of things Brown's done in california," Dorman said yesterday. "Kennedy looks interesting and exciting.

"A Kennedy candidacy would be a labor of love for a lot of us," McDonough said. "We wouldn't just do it -- as we have in the past -- because it's an election and you have to support somebody. It would put the fun back into campaigning here for the first time in awhile."