If, as now appears likely, Todd Akin remains on the ballot in Missouri, it will be very hard for him to overcome the mass condemnation of his own party. He’ll also suffer from a lack of resources, as the NRSC and Karl Rove’s outfit have pledged to withhold funds from the race. Claire McCaskill could find a fairly easy path to reelection.
The Republicans still have pick-up opportunities in Virginia, Wisconsin, North Dakota, Montana, Nebraska, and (theoretically) New Mexico. But they are also looking at tough races in Massachusetts, Nevada, and (perhaps) Arizona. The GOP needs a net pickup of four seats (assuming Obama wins) to take control of the Senate. Without Missouri in play, they’ll have to protect the seats they already have to have any shot at pulling that off.