Last week, Tom Mooney, one of two Democrats who defeated the party slate machinery in the 22nd Legislative District's brawling House of Delegates primary, found what he calls "a political bill" in his mailbox.

It was from Lance Billingsly, the Democratic chairman in Prince George's County.

"He ordered me to pay $400 for my membership in the Democratic team," Mooney said. "And I'm supposed to get six other people to pay $100 for memberships - which, as far as I know, allow you to get drunk at a couple of parties."

The $400 is an assessment to help pay campaign expenses for Democratic slate candidates, and the $100 memberships are a fundraising tactic.

So far, Mooney hasn't paid up, although fellow "outsider" Anthony Cicoria has endorsed the slate and will pay his party assessment. Mooney concedes he may eventually join forces with the entrenched county Democratic organization that he campaigned against in his Hyattsville-based district, but adds, "We have to have some input into the party platform and the campaign."

The outcome of the 22nd District delegate election may very well hinge on the degree to which Mooney, Cicoria and slate regulars Sen. John J. Garrity and Del. Richard Palumbo are able to accommodate one another.

If the Democrats can overcome the memory of the primary campaign, which ended in the defeat of veteran Del. Charles (Joe) Sullivan and organization favorite Mildred Harkness, they could win by a landslide in the traditionally moderate district where Democrats have a 3-to-1 voter registration advantage.

At present, however, the candidates and their precinct leaders are as preoccupied with the summer's wounds as they are with Republican House of Delegates candidates David Elliott, Thomas Kelley and Virgil Bowers.

"A lot of party workers are very despondent about the primary," said Garrity, who has no Republican opposition in the district's state senate race. "They're very bitter about some of the things that went on in the (primary) campaign."

Much of the Democratic organization's post-primary criticism has been directed at Circoria, despite his quick support of the party slate after the primary voting. A 36-year-old Hyattsville trophy and gun shop owner, Cicoria finished second in the primary - behind Palumbo - after assembling his own campaign organization of 200 volunteers and spending $8,000, far more than any of his opponents.

Party workers who supported the defeated slate candidates - as well as supporters of Mooney - are still simmering over Cicoria's campaign tactics, which included running a photograph of the candidate embracing Rep. Gladys Spellman, who subsequently issued a statement denying the implied endorsement.

Cicoria's critics say that he claimed endorsements from other persons - most notably U.S. Rep. Peter W. Rodino Jr. (D.N.J.) and 27th District Delegate Fred Rummage - who also did not support him. Cicoria insists, however, that "we ran a good, clean campaign."

Democratic officials with knowledge of the district's percinct workers now predict that at least 25 percent of them will do nothing to help Cicoria in the current campaign.

Mooney, in contrast, is respected by party regulars for his unbounded enthusiasm for campaigning, which has already driven him to the doorstep of every registered Democrat in the district twice in the last eight months. But Mooney, 34, who has formed a partnership of sorts with four other successful party outsiders in the county, is threatening to abandon the party organization altogether and once again manage his own campaign.

Palumbo, 40, a former assistant state's attorney and still a Democratic Central Committee member, has a solid constituency in the district, no problems with his fellow Democrats and, observers say, negligible chances of losing to one of the Republicans.

Should one of the Democrats falter, however, Elliott, a former chairman of the Washington Suburban Sanitary Commission, is given the best odds of executing a Republican upset.

Elliott, 60, who was soundly defeated in 1974 by former State Sen. Meyer (Manny) Emmanuel in the 22nd District election, has launched his campaign with an aggressive week of doorknocking and a rather unorthodox piece of campaign literature.

The leaflet is sized and designed to resemble the cover of a news magazine and bears the masthead "World Times News Review." Beneath the heading is a photograph of Elliott and a headline that proclaims, "Our Leader of the Year: Elliott."

Elliott, who says he checked the title of the "magazine" with the Library of Congress to ensure that he was not borrowing the name of a bonafide publication, said that such innovations are necessary in a campaign where there are no real issues.

Bowers, 70, hopes to distinguish himself from his opponents by his advocacy of tougher crime laws and penalties. A former commissioner at the Hyattsville police station, Bowers would advocate mandatory prison sentences for repeat offenders who drive while drunk or commit assaults.

Kelley, 28, a warehouse supervisor at the Government Printing Office, favors no-fault divorce and auto insurance, competency exams for students in the sixth, eighth and 10th grades and limits on further development, in the county.