In the East Room of the White House yesterday afternoon, waiters lined up rows of delectable pastries on silver trays and doublechecked the supply of tea and coffee in the elaborate urns. A few feet away in the Grand Foyer, Rosalynn Carter stood beneath the Great Seal of the United States and prepared to greet the wives of members of the 95th and 96th Congress.

It was another reception for which the White House easily shifts its gears but one that could win points for the White House in its difficult courtship of Congress. For 20 minutes, Mrs. Carter, dressed in a chocolate-brown dress and standing with Susie Skelton, the president of the last freshman class of congressional wives, shook hands.

At one point, Mrs. Carter stopped Anne Badham of California, admiring her gold medallion. On one side was an official medal of Congress and on the other her husband, Robert, a second-term Republican, had inscribed, "Well, I love you more than anything in the world," Badham locked eyes with the president's wife, laughing, "That's my congressional medal of honor for campaigning."

Coming through the line were not only 100 wives and a smattering of adminstration officials but a few mothers and mothers-in-law. Jeane Wendt, the mother-in-law of Ohio Democrat Don Pease, had visited the White House last year as a tourist. "But now I'm really proud," she said, looking at her daughter, Jeanne. Edna Beilenson, the mother of Beverly Hills, Calif., Democrat Anthony Beilenson, is a New York publisher but she didn't take the opportunity to pursue Mrs. Carter for a book contract. "Just pleasantries," remarked the publishert.

In the East Room the noise was deafening. Maybe it was because a dezen of the wives had just come from their bimonthly prayer meeting. But when Mrs. Carter walked onto a stage that was still standing from a dinner the other night for the nation's governors, she had to ask three times for attention. She spoke about the partnership a political wife has with her husband. "There's a sense of fulfillment that goes along with the position," said Mrs. Carter. "If you have anything special on your mind, please say so."

One had a personal crisis. Every time she gose home from a white House reception, Laura Leach of Louisiana told Mrs. Carter, her 11-year-old daughter, Mary, wants to know about Amy. That started an animated conversation among Leach, Mrs Carter, Sheila Anthony, wife of a new Democrat from Arkansas, and Nancy Moore, wife of the White House congressional liaison. All have 11-year-old daughters.

Since the purpose of these receptions is fellowship, the social scuttlebutt wipes out any political differences. Alfred Kahn, the Carter inflation troubleshooter, was surrounded by women quizzing him on gas rationing. It was all cordial.

One purpose of the reception was orientation to town but that was unnecessary for Lynn Cheney, whose husband -- a Ford White House veteran -- is now a Wyoming congressman. "The change means making friends with people in a whole other world of Washington, as well as keeping the old Ford friends," said Cheney, who has a political novel "with a fictitious White House" coming out in June.

Towering over most of the women and men in the room was Pat Exon, 6-foot-tall wife of the Democratic senator from Nebraska. Once a flute player with the Omaha Symphony, she is now an avid painter. "I do realistic oils. In Nebraska there were barns, landscapes. Since I've been here I just love the trees. Washington has beautiful trees. And the snow. I am sure everyone else hated it but I did a snow scene and hung it over the fireplace."

One wife said she was "just too bashful" to talk to Rosalynn Carter about her concerns for the physically handicapped. Cheryl sensenbrenner, 28, wears a leg brace, a carryover from injuries suffered in a car accident six years ago. "That's one area I want to get into in Washington," she said, but so far, her greatest problem "has been convincing the Copitol Hill grards I am a wife. Congressional wives aren't supposed to have acne."