District of Columbia Republicans, isolated and alone for the last four years with a Democratic administration in an overwhelmingly Democratic city, may soon find a new rebirth of prominence in city affairs when President-elect Ronald Reagan comes to town.

Although outnumbered by Democrats 9-to-1 in registered voters in a city that gave President Carter 75 percent of its votes Tuesday, D.C. Republicans will likely be the ones consulted when the new adminstration begins deciding on various appointments and making policy decisions that will have a long and wide-raning impact on the city.

Among the federal largess to most directly affect the District, Reagan will be able to appoint judges to the D.C. Superior Court and the D.C. Court of Appeals and select a new U.S. attorney for the District of Columbia. The White House also chooses members of the National Capital Planning Commission and the Pennsylvania Avenue Development Corporation, which is supervising a $2 billion project to develop the main street of the nation's capital.

The city's budgetg must be presented to Congress with recommendations from the president's Office of Management and Budget, and federal agencies from the Department of Housing and Urban Development to the Department of Energy dole out millions of dollars in grants to the District each year.

Local Republicans already are planning for the innaugural activities Jan. 20, in which they plan to play a major part. And party chairman Robert S. Carter has already set up a patronage committee, according to national committee woman Patricia Bruns.

"They laughed at us one time, but they won't laugh again," said lawyer Clarence V. McKee, a Reagan domestic affairs adviser and a longtime District Republican who worked as an obscure researcher in Arthur A. Fletcher's ill-fated Republican campaign for mayor in 1978 but will join the president-elect's Adminstration of Justice Task Force during the transition period.

"Republicans in the District are going to be very important right now," McKee said, "Especially with the close ties the Committee to Rebuild has with the Reagan campaign."

The Rebuild Committee was the group of 67 old-line Republican stalwarts, mostly Reagan supporters from Ward 3, west of Rock Creek Park, who took over the local Republican party from the more moderate-to-liberal wing in a power coup last May.

Of the members of the Rebuild Committee, Carter, the new local party chairman, managed the 1980 Republican convention in Detroit and serves as an executive assistant to Reagan campaign manager William Casey; Bruns and Michael Doud Gill, a nephew of President Dwight D. Eisenhower, are national committee members; and other Rebuilders held various positions high in the Reagan campaign staff and at the July convention in Detroit.

Also, members of the old local party leadership ousted in the May power coup were mostly supporters of George Bush, and several were Bush delegates to the Republican National Convention. They will enjoy access of their own to the vice president while the "Rebuilders" covet their special relationship with Reagan.

"Obviously, access to the White House will be there," said Melvin Burton, a local attorney and Bush delegate who co-chaired the Reagan campaign in the city. "The Bush effort was part of the whole victory. You have Reagan on the one hand and Bush on the other."

Said national committeeman Gill, "We not only have access directly to the White House, but also to the vice president."

Gill said, "As a matter of course, we will be consulted on any appointments to the District. And from our ranks will come people who are natural appointees, which would give us even greater access. One thing's for sure -- Mayor [Marion] Barry's going to have to confer with us more than he did. He will have to consult us in the future.

National committeewoman Bruns put it more simply; "I think all Republicans will be biggies."

The city's Democratic leaders, accustomed to special favors from Jimmy Carter's White House, could find themselves more on the outside looking in, with fewer friends in the new administration and even fewer in the new Republican Senate.

Barry said Tuesday night, at a victory party at the Mayflower Hotel, that Reagan's election "will make my job a thousand times harder." He declined to elaborate.

Sterling Tucker, former City Council chairman and now an assistant secretary in the Department of Housing and Urban Development in a lame-duck administration, said yesterday, "The city will have to make its case, and not just assume things" like it did under Carter. "The city will have to establish a relationship" with the new administration.

City Council member John Ray (D-At Large), who was reelected Tuesday, said, "The District will be looked at much closer now. If we had a high standard before, we're going to have a higher one now. [And] I think a lot of the things we were trying to do are not going to get anywhere with this Congress."

One Democrat whose fortunes are likely to improve will be the council's newest elected member, realtor H. R. Crawford from Ward 7 who was an assistant secretary at HUD the last time the Republicans controlled the White House. "I'm sure that I'll have an ear," Crawford said. "I'll be in a very good position. I've always had a good relationship with Republicans over there [at HUD]."