With the campaign barely one week old, the Republican and Democratic candidates for county executive in Prince George's County have already accused each other of misdeeds high and low in a pattern that is expected to mark one of the most intense political contests in county history.

During the first 10 days:

Lawrence J. Hogan, the Republican challenger, unveiled a "Kelly waste watchers" club that he said will periodically reveal "blatant waste" in the administration of Democratic incumbent Winfield M. Kelly.

At his first "waste watchers" press conference, Hogan charged that Kelly allowed one of his aides, John McDonough, to drive a county car to law school in Baltimore and permitted another aide to purchase, at county expense, an AM/FM radio and new antenna for his county car. Also, according to Hogan, taxpayers had to foot the bill for various luxury items, such as a sun roof, for Kelly's county-owned car.

Kelly, in response, displayed receipts and checks to prove that he personally paid for all the luxury items in his county-owned Ford LTD. He said that McDonough graduated from law school months before he was given a country car and thus could not have used it to drive to Baltimore. And the AM/FM radio, Kelly said, was approved by former central services chief Darrell Clearwater, who now is a Republican candidate for County Council.

Kelly said that Clearwater is the source of Hogan's "waste watchers" material and was motivated by the fact that Kelly fired him from his central services job. The county executive, who rarely speaks ill of his enemies, called Clearwater "undoubtedly the most incompetent bureaucrat I've dealt with since I entered county government" Clearwater said, for his part, that he has a letter from Kelly praising his work.

Kelly, at his first campaign press conference, charged that Hogan was "immoral and unethical" for failing to identify the sources of nearly $10,000 the former Republican congressman raised during the primary. Kelly said Hogan's technique of identifying the contributions merely as ticket sales was "a practice that I thought went out with high-button shoes."

Kelly said that he has made public every donation to his campaign, large or small, and that Hogan should do the same. "Until that happens," he said, "there will be serious questions as to how Hogan is getting his money."

Hogan responded that the $10,000 came in ticket sales to a $25-per-person fund-raiser at The Plum discotheque in Washington and that all of that money came in amounts below $50. He noted that state law requires the disclosure of contributors who give more than $50.

While opening his contribution books to reporters, Hogan said he would not publicly reveal the names of persons who donated $50 or less to his campaign because he feared they would be subject to retribution by the county's powerful Democratic organization.

"Many hundreds of county employees and Democrats came (to The Plum find-raiser)," Hogan said. "In the past, Democrats who contributed to my campaigns were intimidated and threatened by the Democratic machine."

One of Hogan's closest allies, John Hanson Savings and Loan president Gerard Holcomb, charged that many of his colleagues in the Prince George's business community had been told by Kelly to "zip up your wallets" and not contribute to Hogan.

Kelly and his aides denied that they were pressuring financiers not to contribute to Hogan and suggested that Holcomb, a member of the county liquor review board, had a reputation for using strong-arm tactics to raise money.

Hogan challenged Kelly to an old-fashioned, outdoor debate at "the dueling grounds in Bladensburg," the historic site where Aaron Burr dueled Stephen Decatur.

Kelly aide John Lally said the "dueling grounds" debate was "the silliest thing I've ever heard" and argued that Kelly and Hogan would be able to debate at several forums and on television. "We're not going to trudge out to a grassy knoll next to a Frito-Lay potato chip factory and make a mockery of this campaign," said Lally. "Jeez, we've got a million debates already scheduled."

Although the give-and-take of the first week apparently missed the mark so often that one county politician likened it to "The Gang That Couldn't Shoot Straight," it set the stage for a race that promises to be one of the most hard-fought in Maryland this year.

On one side is Winfield M. Kelly Jr., age 42, a millionaire who made his financial fortune during the county's boom years by selling half-smokes and soup to construction workers. He has attempted, politically, to duplicate his personal success story in a county that has long suffered from an inferiority complex through what he has called a "New Quality" campaign.

On the other side is Lawrence J. Hogan, at age 50, a former FBI agent who three times was elected to Congress by appealing to the county's blue collar and conservative constitutency during the antibusing and Vietnam War eras.Hogan also has developed a reputation as one of the most adept and popular politicians the county had seen.

The political interests of the two men are broader than the confines of Prince George's County: Hogan unsuccessfully ran for governor in 1974; Kelly would like to run for governor in 1982 or later. Both are well-liked by the county's business establishment, and both are somewhere in the middle of the idological specturm.

Both candidates like to say that the 1978 county executive race will be decided by one issue: who can best manage the multimillion dollar business of county government. Their party colleagues say almost unanimously that the race will be decided by personalities, not issues.

At this early stage, even Kelly agrees that he is behind in the popularity contest. Hogan says his polls show him "way, way ahead." Kelly says that he has closed the gap, but still trails. As Kelly sees it, the county executive's position is one political office where incumbency is a disadvantage.

"Look around the state this year," Kelly said. "Several county executives were beaten in the primaries; others decided not to seek reelection and might have lost if they had tried. In Prince George's, a County Commission chairman or county executive has not succeeded himself since 1950. It's got to be the most unpopular job in government. It's like the emergency ward of a hospital - everyone wants you to fix things right away."

"Winnie can't win it, the way I see it," said Hogan. "The only chance he has is if I lose it. Two things are coming together in a vortex - the hostility toward Winnie and the fact that so many people remember and like me from my days in Congress. I was shocked myself by the number of Democrats who told me on primary election day that they'd support me. At every polling station, I encountered Democratic precinct pollworkers who said: 'Larry, I'm with you.'"