Tomorrow, Obama will travel to college campuses in Columbus, Ohio, and Richmond, Virginia, to mark the start of his general election bid, yet much of the groundwork for the contest already has been quietly put in place.
33 out of 100 seats are up for election. 51 are needed for a majority.
|Seats gained or lost||+2||-2|
* Includes two independent senators expected to caucus with the Democrats: Angus King (Maine) and Sen. Bernie Sanders (Vt.).
All 435 seats are up for election. 218 are needed for a majority.