SINCE AUDREY Towater started frequenting Dad's Art Shop, her local art supply store in Scottsbluff, Neb., her career has taken off as fast as her paint brush.

For two days recently, Towater turned the chandeliered Congresswomen's Suite on the second floor of the Capitol into her private studio, and almost met her goal of painting all 21 women members of the House. As the representatives drifted into the room that once was used by John Quincy Adams, Towater captured 18 portraits on canvas in less than seven minutes each.

"I guess you could call me an on-the-spot artist," says Towater, whose main occupation before she turned to art four years ago was raising three children with her husband, Lou, president of the American Beet Grower's Association. "I go even faster when I'm painting a football play, and have to get both teams on a 20-by-40-inch canvas." She is talking while she paints.

Sketching Marjorie Holt (R-Md.), she balances the canvas on the lap of her spattered black slacks. Holt stands in the doorway of the room while Towater squeezes some blue paint from a plastic tube ("I only use acrylic paint because it dries fast, and I can paint over it") and fingerpaints the shape of Holt's dress in two seconds flat. Then Towater switches to a brush, putting in detail, smoothing out lines, getting the eye color and facial expression. She even manages to paint in Holt's pendant, a gold dagger from Oman. Just then, two bells sound in the room, echoing off the vaulted ceiling, and signaling to Holt that she must return to the floor for a vote. But Towater, her curly black hair flecked with paint, has already finished. "Beautiful," smiles Holt, as she hurries out.

"I still can't believe that I'm here, that I'm doing this," says Towater, gesturing around the narrow room from her folding chair. Her eyeglasses have green globs of paint on them, and her dropcloth and hands are covered with other colors. Already that morning, she had painted representatives Barbara Kennelly (D-Conn.), Beverly Byron (D-Md.) and Marilyn Lloyd Bouquard (D-Tenn.), sitting on the Empire-style couch that was Adams' deathbed when he collapsed on the floor of the House in 1848. Earlier, Towater posed other representatives in front of the mantelpiece and gilded mirror that reflects the 1910, five-tiered chandelier in the center of the room. Her brightly colored work--six group portraits in all--may soon be gracing the walls of the Capitol; she plans to submit the paintings to the Capitol architect's office, which decides if and where they will be hung.

Towater first offered to paint the representatives in 1980, after painting her local representative, Republican Virginia Smith, at a meeting of farm owners' wives in Nebraska. Smith and Towater have known each other for years. Smith wrote to the other representatives, advising them that the artist would be coming to Washington, and Towater's first visit, though brief, had dramatic results. "I was going to paint a congressional hearing," she recalls. "I came in early to paint in the background--empty chairs and tables. Then I heard the news on the radio. The president had just been shot. I was stunned, everyone was in the corridors, listening to the news. I was so upset, I changed my airline ticket and flew right back to Nebraska."

The dark, somber-toned painting of the empty hearing room stayed in Towater's collection; she titled it "A Nation in Shock." A business associate of the artist told the White House about it. Next, she says, the White House wrote her, asking if she would send the picture. The painting is being stored in the Archives building, according to the White House.

Towater talks about her work to everyone who will listen, including members of Congress. On the Hill, she had large prints of her paintings all around her as she worked in the reading room. "Did I tell you that I just finished painting Placido Domingo singing in La Boheme at the Colorado Opera?" she asks Barbara Kennelly. "I painted by flashlight, and it was probably the most difficult piece I ever did. When I went over to the orchestra rail, I dumped my paint water on the violinists. Everything stopped dead." But the conductor smiled, the music for the dress rehearsal resumed, and Towater finsihed her painting of a scene in Mimi's Paris garret.

Towater, who never gives her age, says she has done at least 280 works since 1979, from family portraits to a hot-air balloon show to an oil rig ("I like the details of nuts and bolts"). She has two oil wells of her own on her family's 800-acre property in Scottsbluff.

Towater admits, "I guess I do a great sales job for my work. I get lonely by myself. It can be scary going to a new town to paint, so I love meeting people. At home I don't have a studio, I paint in the living room, while my husband watches TV. But also I'm highly motivated, and I want to be internationally famous in my lifetime."