For six hours every day since last January, Tom Mooney has been walking the streets of Hyattsville, University Park and Chillum. In the course of his journey, Mooney has encountered 19,000 Democrats, two dogs, one bee and a spider. The Democrats took his literature and listened to his political spiel. The other creatures bit or stung him.

Mooney, a candidate for the House of Delegates in the 22nd Legislative District, is not to be deterred by ungracious animals. "If there's a home with six registered Democrats in it," he boasts, "I'll tangle with a python to get to the door."

There are a few regular Democreats in the district who would love to see that happen.

In the parlance of Prince George's politics, Tom Mooney is an outsider, a candidate who is seeking office without the blessing of the dominant Democratic organization. Not only is this red-faced Irishman running against the organization, he is considered to have an excellent chance of beating it.

"You've got to remember that this guy (Mooney) has been out there campaigning door-to-door for years," said state Sen. John J. Garrity, the leader of the organization ticket in the Hyattsville-based district. "When someone works that hard, you can't take him lightly."

Mooney is not the only outsider who is thought to have a chance of upsetting the organization Democrats in the arrowhead-shaped district on the western edge of the county. Hysattsville businessman Tony Cicoria, a delegate candidate, and Claire Bigelow, who is challenging Garrity for the senate seat, also are conducting energetic campaigns.

If one or more of the outsiders win, as many observers expect, it would be a double embarrassment to the party regulars. For this is the district that has long been considered a model of organization politics and it is also the homeland of two prominent party leaders - County Executive Winfield M. Kelly Jr. and Democratic chairman Lance Billingsley.

The weakening of the organization structure in the 22nd can be traced back to the resignations of two veteran legislators in recent years. State Sen. Meyer (Manny) Emanuel resigned in 1977 when he moved to a house farm in the southern part of the county. Del. Ann Remington Hull resigned this year to take a job with the national League of Women Voters.

Emanuel and Hull, both liberals were among the more respected members of the Maryland General Assembly. They were regarded as conscientious and intelligent lawmakers and were often cited by leaders of the county organization as proof that the so-called Democratic machine was progressive and open-minded.

Their departure hurt the organization in two ways. First, it left conservative Gerrity as the leader of a moderate-to-progressive community. Second, it left the organization open to charges of machine politics for the manner in which they were replaced.

With little attempt to hide their motives, Kelly and other party leaders directed the series of maneuvers that led to Garrity assuming Emanuel's seat, former Hyattsville councilwoman Mildred Harkness taking Garrity's delegate position and Democratic Central Committeeman Richard Palumbo replacing Hull on the delegate slate.

Although all three maneuvers were said to be the results of a democratic selection process, virtually every active Democrat in the county knew who would get what position long before the actual fact.

Harkness and Palumbo, the main beneficiaries of organization reshuffling, are now fighting for their political survival in delegate races against Mooney and Cicoria. Party leaders say privately that they are concerned one or both of them will lose.

The third delegate candidate on the organization slate, Charles (Joe) Sullivan, an eight-year veteran in Annapolis, has quietly set himself apart from his running-mates. He has done much of this door-knocking alone and, a few weeks ago, appeared at a campaign coffee with Mooney. The organization has expressed some disappoint with Sullivan's solo approach, known in the jargon as "single-shooting," but he is thought to be a sure bet for reelection.

Except for Bigelow, a liberal women's activist who opposes Proposition 13-style movements, supports measures that would make the income tax the major source of the state revenur and supports state-financed abortions, the candidates in the 22nd have for the most part not based their campaigns on specific issues.

Mooney, who lost by only 400 votes in 1974, says openly that he is counting on his legwork, not his positions, this year. "We're not running on substantive issues," he said recently. "We're running on personalities."

Most of the candidates have discovered during their door-knocking ventures that the most controversial personality in the district is County Executive Kelly, who is also seeking reelection. "The anti-Kelly mood is everywhere," said Cicoria. "The only negativism I hear is about Win Kelly," said Sullivan. "The people I talk to say he hasn't done a good job."

Garrity, who served on the old county commission with Kelly for four years, is one of few candidates in the district who is not openly afraid that Kelly will hurt the ticket. "The economic issue is paramount," said Garrity, "and I think Winnie has done an excellent job defusing that issue. He's lowered the tax bills."

Along with Garrity and Bigelow, the Senate candidates include Thomas C. Neal, who has spent the past four years protesting the Democratic machine, and Frances Patricia O'Hare, the daughter of Orphan's Court Judge Mary O'Hare and fiancee of DelPerry O. Wilkinson, who was dumped by the organization in the 23rd District. Eleanor Cortez, a politicl newcomer from Hyattsville, is running in the delegate primary.