Will Feingold run for re-election to the Senate in 2004? His seat was up that year.
If you recall that Paul Ryan ran both for his congressional seat and the Vice Presidency in 2012, so there's no law in Wisconsin, (LBJ law) preventing a candidate from running in two federal elections, so
Feingold can do what Paul Ryan was able to do 😉... there are similar laws in place in Arizona, California, Connecticut, Delaware, Indiana, Massachusetts, North Carolina, Ohio, Pennsylvania, Tennessee, Texas and Utah 😉