Linda Bove and Peter Evans, the stars of "Children of a Lesser God," smiled and stood for cameras that flashed blinding explosions of light in the darkened room. Bove's sign-language interpreter was ready behind her.

Sen. Charles Percy (R-Ill.) came up and grasped her hand as more flashbulbs went off at the opening night party next door to the National Theatre. He pointed to his own hearing aid in his left ear. Then he went and got Secretary of Health and Human Services Richard Schweiker and Percy pointed out Schweiker's hearing aid.

"I find when I put it on," Percy had said earlier, grinning, "people speak up."

Percy, who loved the play, also got a chance to recapitulate the plot to his colleague, Sen. John Heinz (R-Pa.), who got tied up on the Hill and arrived 20 minutes before the end.

But there were still enough members of Congress and Washington notables to gush enthusiastic kudos while drinking champagne and eating plump strawberries, something they haven't been doing for the last few days.

"What a week it's been," said Rep. Patricia Schroeder (D-Colo.). "Everything has kind of stopped. It's been somber and sad."

Schroeder was asked whether she thought the assassination attempt on President Reagan would garner sympathetic support for his programs in Congress. "We can question programs without questioning him personally," she said. "That's the intellectual answer. But politically, people might be afraid to question him."

As for the play she had just seen, "my hands are weak just from watching," moaned Schroeder, referring to the two main characters, who use sign language continually.

But Peter Evans still had enough energy to keep doing what he had been doing the previous two and a half hours. He interpreted questions for Linda Bove when the other interpreter wasn't around. Chatting with her in sign language while holding a glass champagne proved precarious. as some of the liquor in his glass sloshed out onto her hand at one point. She didn't bat an eyelash.

Her description of how opening night went: "Up," she signed, smiling and thrusting one thumb up.

"Marvelous," said Rep. Tom Evans (R-Del.) introducing himself to Peter Evans.

"Hi," said the actor, shaking the congressman's hand. "Are we related?"

Nearby, the playwright, Mark Medoff, autographed someone's posters. "Oh, usually they have to tie me down to watch [the play]," he had said during intermission. "But tonight I don't mind. I haven't seen it in about five months."

Gordon Davidson, the director, sailed cheerfully through the evening, saying the play had gone well -- but he took a few notes on his program during the performance. "I wanted it to be in top shape," he said. "And it is. It's important -- because of Gallaudet College and because of the community." And because of the fact that Davidson, who testified in support of the National Endowment for the Arts -- now facing the prospect of 50 percent cuts -- wants the play (which was originally produced under a grant) to be its own testimony to what can be fostered under an NEA grant.

"It's nice to see something successful that got its start with an NEA grant," said Livingston Biddle, chairman of the NEA.

And did he tell that to the Republican members of Congress present at this party?

"Oh, yes," he said smiling.