Democrats have all but written off at least three Senate seats - in North Dakota, Indiana and Arkansas - and at least six House seats in Tennessee, Louisiana, New York and elsewhere as they begin a big advertising push to minimize congressional election losses.
Republicans recently threw $1.3 million into West Virginia in hopes of winning a Senate seat that was long thought out of reach. It was the GOP's latest move to expand a playing field already heavily tilting its way.
In the one-month dash to Election Day, both parties are zeroing in on races they have the best chances of winning. They're reconfiguring strategies and shifting advertising money by the day. The state of play could change repeatedly between now and Nov. 2.