Actually, Mel Carnahan remained on the ballot. Shortly after the plane crash, new Gov. Roger Wilson announced that if Carnahan was elected, he would name his widow as Senator.
In the two weeks following Carnahans death, there was really no campaigning. But there was a lot of sympathy and a highly publicized funeral, of course. Ashcroft lost by about 2%, or 50,000 votes. It was all done legally, but the sympathy factor had a whole lot to do with it.
Two years later, after we had discovered that Jean Carnahan was slightly dumber than a box of rocks, she was defeated by Jim Talent in the special election.
and of course the legacy continues with more little Carnahans looking to feed at the public trough. It is amazing how many little leftists one family of school teachers can begat.