SDP noted yesterday's New York Times editorial about certain Democrats being mad at Senator Frist for coming to South Dakota to campaign against Daschle (also note today's NYT's editorial about the Senate and the filibuster, which Daschle will be remembered for). As to Senators campaigning against one another and the idea that this "unprecedented," note this about South Dakota Republican Senator turned silverite Richard Pettigrew and his 1900 re-election effort (pre-direct election, i.e. when state legislatures still picked Senators) from Hebert Schell's classic History of South Dakota (p. 240):
A number of nationally known figures came to South Dakota to make the renegade Senator their special target. Among them were Theodore Roosevelt, the Republican nominee for vice president, and Marcus A. Hanna, chairman of the Republican National Committee, both of whom had been subjected to personal abuse in the Senate by Pettigrew.