A half-dozen potential presidential candidates began ramping up their political action committees over the past six weeks as they weigh whether to enter a still-empty race for the Republican nomination in 2012.
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.