Birthday bonanza. Political plethora.

Del. Walter E. Fauntroy (D.-D.C.) celebrated his 49th birthday Friday night. Following suit Saturday night, Mayor Marion Barry celebrated his 46th. And though disguised as birthday celebrations, the two parties held for them were fund-raisers, steps along the campaign trail of city politics.

Friday's:

The place: the Washington Hilton. The time: 8 p.m. The occasion: birthday. Attire: semi-formal. Guests trickled into the dimly lit ballroom, greeted at the door by three women handing out tickets for the night's fur hat raffle. Balloons and buttons imprinted with FAUNTROY FAMILY waved above tables and rested on lapels.

About an hour into the evening, Fauntroy arrived with his wife, walking past a room dotted with empty tables, to the head one. Surrounding him at three tables were 14 relatives.

Describing himself as "not a connoisseur of fashion," Fauntroy took a minute for reflection as several models glided past on the long runway set up in the middle of the room.

"It's been a bittersweet year," he began. "Sweet because for the first time, the Congressional Black Caucus came up with a constructive program for the legislative budget . . . bitter because the budget did not find support."

But Fauntroy did not spend the evening dwelling on the past. After the fashion show, Count Basie struck up his band, Fauntroy led off the dancing and the politicking began. As Fauntroy went one way around the horseshoe of tables smiling, shaking hands and patting backs, Barry, who had come with birthday wishes for Fauntroy, headed the other way around the room. Between them, there were other flesh-pressers in the crowd, including Council members Betty Ann Kane, Charlene Drew Jarvis and John Ray.

"I'm not politicking tonight," Ray said. "I'm celebrating. Besides, you know, sometimes you can politic better by not politicking."

After making the rounds, Fauntroy took the stage, a cake was carried to him and he announced "one of the best kept secrets in the world"--his intention to run for reelection.

Saturday's:

The place: Georgetown Park. The time: 10 p.m. The occasion: a birthday. Attire: semi-formal. At the stroke of 10, Washingtonians began to pour into the spiffy new shopping mall which, closed to the public, was adorned with red and white balloons, bouquets of flowers and tables loaded with beer and wine, cheese and crackers, petits fours and coffee.

But much of "the public" made up the over-1,000 crowd which milled around the mall's three levels greeting fellow businessmen, community members and friends.

"Many of the people here tonight were here four years ago," said Ted Gay, chairman of the D.C. State Democratic Committee. "They're a part of Barry's army."

And the ranks of that army surrounded him, asking him to pose while their Instamatic cameras flashed. While his wife, Effi, held one hand, Barry offered the other to anyone near him. Some constituents leaned over the railings of two floors while others crowded around him.

"It is my real birthday, of course," Barry said, after heaping the usual praise on the campaign donors. "My mother called me this morning and told me so."

But the real reason for the party was not forgotten.

"I haven't had to use a map to find you. I know this city very well. I'm proud to be your mayor," Barry said, while the crowd cheered. "And remember: It's on to victory, On To Victory, ON TO VICTORY . . . "