Grayson is running against Patrick Murphy for the Democratic nomination.
Reince Priebus thinks Republicans will keep the chamber, but says it will be unpredictable.
This is part of a campaign against vulnerable Republicans running for Senate.
The first spots will target Sen. Pat Toomey.
Sanders, a long-shot, says he's thinking about the "enormous responsibilities" of the job.
Democrat Catherine Cortez Masto hopes to replace retiring Sen. Harry Reid.
Jim Obergefell endorsed Ted Strickland over Sen. Rob Portman (R), who's embraced gay marriage.
The pro-abortion-rights group shared its new line of attack with The Hill.
The Republican incumbent faces a tough challenge from Gov. Maggie Hassan.
The DSCC accuses the New Hampshire Republican of "rewriting her record."