WASHINGTON -- The day after Beverly Byron's congressman husband dropped dead at age 48 while training for the Marine Corps marathon, the governor of Maryland sat in the widow's living room, urging her to take his seat.

"My two boys said, 'She'll run.' I said, 'I will?' They said, 'Yes.' It was the best decision they ever made," recalled Byron, a House member from 1978 to 1992, twice as long as her husband.

"In 24 hours, I became a widow, a single parent, unemployed and a candidate for Congress," she said. "I knew I needed to work. It was the only job offered to me."

Succeeding a politician who dies in office has long been a woman's surest path to electoral success: Among first-time House candidates from 1916 to 1993, 84% of the widows won, while only 14% of other women were victorious. The trend was strongest when women were rarer in politics; 35 of the 95 women who served in Congress through 1976 were congressional wives first.

Now, with more than 1,500 female lawmakers nationwide and 100 women expected to run for Congress this fall, the so-called widow's mandate seems in vogue again, as the current California political landscape vividly demonstrates.

Democrat Lois Capps, her husband Walter's sidekick on the campaign trail and in Congress until his fatal heart attack Oct. 28, is favored to win a March 10 special election in the Central Coast district. Republican Mary Bono, a former waitress who said "no" when Larry King asked last week whether she was politically involved, is the only announced candidate to fill the House seat vacated this month when her husband, Sonny, died in a skiing accident.

If elected, they would join Rep. Jo Ann Emerson (R-Mo.), who won husband Bill's seat after he died of lung cancer in June 1996--the first instance of matrimonial succession since 1985.

Historically, party leaders anointed widows to honor the deceased member, tap voters' sympathy and exploit name recognition to hold onto a seat while more conventional candidates prepared for the real campaign. For many of the women, taking their husbands' seats helped them grieve--and made up for the sudden loss of income in a world where few worked outside the home.

But frequently, a funny thing happened on the way to Congress: Widows who passively accepted political posts during the daze of mourning often decided to stick around, sometimes bucking the will of those who had tapped them.

Several outlasted--and outshined--their husbands.

"Very often, the wife turns out to be a hell of a politician," said Stephen Hess, a political dynasties expert at the Brookings Institution, a Washington think tank. "You talk about founding fathers, but there were founding mothers too. These political families were often a twosome."

Political scientist Diane Blair examined the phenomenon in a 1978 paper titled "Over His Dead Body," and later wrote a biography of the first woman elected to the Senate, Hattie Caraway (D-Ark.), who served from her appointment in 1931--after her husband's death--until 1945.

"Behind a strong member of Congress is [often] a very supportive and insightful spouse," Blair said in an interview. Assuming a dead husband's place in office "was a natural extension" for such women.

Caraway carved the mold of a widow selected as a bench warmer who forged her own political career--despite the protests of her husband's cronies.

"The time has passed when a woman should be placed in a position and kept there only while someone else is being groomed for the job," Caraway said in announcing her surprise plan to run for election in 1932 against several Arkansans coveting the seat.

A homemaker whose only political experience was lunching with other Senate wives, Caraway was given a back-row seat and forced to use the public restroom. She took her knitting onto the Senate floor, observed upon first entering the chamber that the windows needed washing, and never made a speech. "I haven't the heart to take a minute away from the men," she said. "The poor dears love it so."

But some historians say "Silent Hattie," whose portrait was unveiled in the Capitol last year, was active behind the scenes and took care of her constituents.

"From our perspective, we would certainly wish that she had been more outspoken," Blair said. "But it's rather unfair of us to impose our expectations looking back at a woman who faced some really daunting obstacles."

Counting Caraway, seven of history's 26 female senators were congressional widows, including Margaret Chase Smith (R-Maine), who filled her husband's House seat when he died in 1940, moved to the upper chamber nine years later and stayed until 1972, when she finally lost an election. Smith was her husband Clyde's secretary, drove his car on the campaign trail and called herself "a living symbol of nepotism."