The internecine warfare within Montgomery County's Democratic party escalated last week, with party outsiders retaliating against a newly formed slate of incumbent Democrats and their handpicked running mates.

Tony Fisher, a party newcomer running for sheriff, is threatening to file a complaint against the local party with the Democratic National Committee. Fisher, who is black, is charging that the process used to select candidates for the incumbents' slate is undemocratic and discriminatory against blacks since there are no black incumbents.

Meanwhile, the traditionally liberal group called Alliance for Democratic Reform has responded to the incumbents' ticket by putting together its own slate of candidates, including some outsiders left off the incumbents' ticket.

The center of the controversy is the incumbents' slate, called "Democrats for '82," which includes candidates for all offices but County Council. The ticket, officially unveiled on Monday, will be headed by Gov. Harry R. Hughes, Sen. Paul Sarbanes and Attorney General Stephen Sachs, and will include Rep. Michael Barnes, County Executive Charles W. Gilchrist, State's Attorney Andrew Sonner, four sitting judges, Sheriff Jim Young, various court house incumbents and state legislators, and members of the central committee.

At Fisher's request, the party's central committee voted last Wednesday night to restate its longstanding policy of not taking sides in contested primaries. But the move was not enough to satisfy Fisher, who is accusing the official party of working in an alliance with the incumbents' slate. He also wanted the central committee to hold a press conference three days before the Sept. 14 primary to repeat its neutrality.

"There could be a grievance all the way up to the national party," said Fisher's campaign manager, Maurice Allain. "They have no elected officials in this party who are black--that's not the policy of the national committee. They are involved in a practice that tends to exclude minorities."

Fisher's vigorous campaign for the office of sheriff is likely to turn that race into a shootout. He is stressing his 11 years as a Montgomery County police officer, his degrees in business management and law enforcement and his various awards. He also likes to point out the bureaucratic snafus that have dogged the administration of the incumbent sheriff--like an auditor's report showing that hundreds of thousands of dollars in fees collected were not promptly turned over to the county government, costing taxpayers thousands of dollars in lost interest.

Fisher thought his credentials would win him the official embrace of a party that now has no blacks on its ticket for any office. But the incumbent slate was formed, and the party stuck with the incumbent, Jim Young. "Jim is all right," said slate chairman Victor L. Crawford. "There's been no scandal while he's been in office. Besides, he'll help us up-county."

While Fisher was pressing his case, and attracting some badly needed media attention, the board members of the Alliance for Democratic Reform were busy forming their own alternative slate of candidates, rejecting some longtime ADR activists with liberal credentials in favor of an anti-incumbents slate. Fisher is on the ADR slate, as is Sonner's opponent for state's attorney, Daniel J. Cassidy.

For candidates left off the incumbents' slate, the ADR slate could prove an effective countermeasure, Cassidy said. "I really needed to be on that slate," Cassidy said with a sigh of relief after his inclusion on the ADR slate was upheld by the group's full membership.

Furthermore, the ADR ruled to make it virtually impossible for candidates to be on both slates, forcing their invited candidates to choose between the ADR slate or the powerful incumbents' ticket.

"Either way I go, I'm bound to alienate somebody," said Del. Stuart Bainum, who is running unopposed in the primary for state senate in Legislative District 20. Bainum was one of only nine persons on the incumbents' slate invited to join the ADR slate. The incumbents' ticket has a "loyalty oath" prohibiting any member from giving money to another slate, and the ADR requires a fee of any candidate who wants to join its slate.

"It's the toughest decision I've ever had to make in my short political endeavor," Bainum said.

Another candidate facing the same dilemma is Del. Jennie M. Forehand, who is running for reelection in District 17, which includes Rockville. "I would like to participate on both" slates, she said. "I would like to see a reevaluation of that loyalty oath."

Attorney Stephen M. Nassau was handpicked by the incumbents to fill a vacant delegate slot on their ticket in the Bethesda district. He was also invited onto the ADR slate. "I certainly am sympathetic to ADR and am in tune with their goals," he said. "On the other hand, I've been invited by people who are in office to run with them on their slate. It's a dilemma."

The ADR slate was selected by the group's 19-member board of directors. Because so many longtime liberals and ADR supporters were not invited onto the slate, some ADR members tried to launch a revolt against the board. They began lobbying ADR members to overturn the board's decision at a Saturday night membership meeting set to ratify the slate. Only three of the board's initial choices were knocked off the slate during that Saturday night massacre; Cassidy, Fisher and most of the others survived.

Both the incumbents and the ADR plan to print sample ballots to be mailed directly into the homes to the county's likely Democratic primary voters. But this year, those sample ballots may have less impact than in previous races. For the first time in a county election, the county Board of Elections will be mailing out its own sample ballots, which will include the names of all primary candidates.

"That will really mitigate the effect," Bainum said. "A good Montgomery County civic activist will pick up the Board of Elections ballot before they pick up a sleazy slate ballot."