President Obama stumped for gubernatorial candidate Tom Wolf this weekend in Philadelphia. Wolf's victory Tuesday was among the few bright spots for Democrats. Pablo Martinez Monsivais/AP hide caption

itoggle caption Pablo Martinez Monsivais/AP

Supporters of Republican Sen.-elect Tom Cotton celebrate his win in Arkansas over incumbent Mark Pryor. The GOP picked up seven seats Tuesday, gaining control of the Senate. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

It's a long shot, but there's a scenario where control of the Senate might not be known until Jan. 6 — three days after the start of the next Congress. That's when Republican David Perdue and Democrat Michelle Nunn will face each other in a Georgia runoff if one of them fails to win 50 percent on Tuesday. David Tulis/AP hide caption

itoggle caption David Tulis/AP

Senate Republican leader Mitch McConnell speaks to supporters Saturday at the Tanglewood Farms Restaurant in Franklin, Ky. McConnell faces Tea Party challenger Matt Bevin and several other lesser-known candidates in Tuesday's GOP primary. Timothy D. Easley/AP hide caption

itoggle caption Timothy D. Easley/AP

Oregon Republican Senate candidate Monica Wehby, right, talks to supporter Marvin Hausman in Lake Oswego, Ore. Wehby has drawn national attention and money in her effort to win her party's nomination. Jonathan J. Cooper/AP hide caption

itoggle caption Jonathan J. Cooper/AP

Lt. Gov. John Walsh defending himself in Helena, Mont., on Jan. 26 against reports that he was reprimanded by the U.S. Army in 2010 for using his position as Montana adjutant general to solicit National Guard memberships to a private organization. Matt Volz/AP hide caption

itoggle caption Matt Volz/AP