Maryland Gov. Marvin Mandel, a politician of few philosophical pretensions, once observed that there are two transcendent issues in Maryland politics: "winning and losing."

When he delivered that bried manifesto in 1968. Mandel could not have know that he and his Old Guard school of politics would be THE ISSUE in the Democratic gubernatorial primary 10 year later.

That had been made almost inevitable by the indictment of Mandel and five of his political allies in 1975 on political orruption charges and the disclosures at the 12-week trial of favors the governor received from his co-defendants.

Until the Democratic governor and his friends were convicted last week, the political setting remained murky at best, with some of the major candidates unwilling to commit themselves to a political strategy without knowing if a vindicated Mandel would be a factor in the race.

Now reform candidates are confidently going ahead with their plans to campaign hard on a "clean government" platform harshly critical of what one political organizer called Mandel's "rule by friendship and favor." And acting Gov. Blair Lee III who as Mandel's lieutenant governor would have most benefitted from a not-guilty verdict as a gubernatiorial candidate has already started putting distance between himself and the convicted governor.

In most Maryland political circles, pundits now question what role - if any - will be played by Mandel's statewide political organization, which is a loose-knit networkd of friendships held together by personal loyalty to the convictrd governor and the trusted delivery of campaign day money.

"Tbe best thing Mandel can do is stay out of it," said Phil Altfeld, who is campaign manager for Maryland Attorney Gen. Francis B. Burch, along with Lee and others one of the leading gubernatorial candidates. "He's been convicted and shouldn't be saying who's the next governor."

The convictions of Irvin Kovens, W. Dale Hess and Harry Rodgers III, the state's most powerful political fundraisers, also leaves a vacuum for candidates who plan to run expensive, slick media comapaigns in the fashion perfected by Mandel.

While there is general agreement among political strategists that association with Mandel will be a crippling liability in next September's Democratic primary, most of the major gubernatorial candidates observed a respectful silence about Mandel after his conviction last week.

As the candidate must closely linked with Mandel, however, Lee began the process of dissassiciation a few hours after te guilty werdict when he said at a press conference that Mandel lacked moral leadership and candor.

Lee reiterated the criticism yesterday on Baltimore's WIZ-TV when he told an interviewer that Mandel "had a problem in telling it straight out. I think it goes back to his early training as a Baltimore downtown lawyer defending clients who were guilty as the day is long from the moment they were hauled in."

Despite his stamp as Mandel's lieutenant governor, Lee's ascendance to the governor's seat has made him the acknowledged front-runner at this stage of the campaign. With his access to the rich source of patronage as acting governor and the almost constant glare of publicity, he will have more than a year to cement political alliances and cast himself as a leader.

But his equivocal status as the candidate most likely to be hurt by the Mandel connection as well as the one most likely to benefit from whatever is left of the Mandel loyalties is expected to bedevil his campaign. Lee conceded as much in yesterday's interview when he said, "I'm in a situation where every statement I make . . . everytime I open my mouth, everytime I clear my throat, I get in trouble with somebody."

State Senate President Steny H. Hoyer, another gubernatorial hopeful, pinpointed the dangers of Lee's political status in an interview yesterday on Washington's WJL-TV. "I believe people are looking for a change, which is more than a transition," the Prince George's County Democrat said on the Headliners program.

While the Mandel guilty verdict provides Lee with the advantages of incumbency, it also enhances the campaigns of three "reform" candidates - Baltimore County Executive Theodore G. Venetoulis, who toppled the entrenched county machine in 1974 on a platform of "Throw the Rascals Out;" Harry Hughes, Maryland's former transportation secretary, who resigned in protest last May after charging that there was political tampering with a Baltimore subway contract; and Baltimore City Councilman Walter Orlinsky, who is the product of a liberal Democratic organization.

All three expect to capitalize on Mandel's political demise. One of Venetoulis' campaign strategists sounded the theme in an interview last week when he said, "The whole Annapolis crowd is in disgrace now. The farther away you get, the better Off you are."

Two other candidates - Burch and State Comptroller Lous L. Goldstein - have, like Lee, run on statewide tickets with Mandel. Although they have carved out their own political identities over the years, both are expected to be questioned about voters about past associations with the convicted governor.