Only 10 Democrats are up for re-election in 2016 - and 24 Republicans. Looks good for Democrats.
DEMOCRATS
Michael Bennet (Colorado)
Richard Blumenthal (Connecticut)
Barbara Boxer (California) retiring in 2016
Patrick Leahy (Vermont)
Barbara Mikulski (Maryland)
Patty Murray (Washington)
Harry Reid (Nevada)
Brian Schatz (Hawaii)
Charles Schumer (New York)
Ron Wyden (Oregon)
REPUBLICANS
Kelly Ayotte (New Hampshire)
Roy Blunt (Missouri)
John Boozman (Arkansas)
Richard Burr (North Carolina)
Dan Coats (Indiana)
Mike Crapo (Idaho)
Chuck Grassley (Iowa)
John Hoeven (North Dakota)
Johnny Isakson (Georgia)
Ron Johnson (Wisconsin)
Mark Kirk (Illinois)
James Lankford (Oklahoma)
Mike Lee (Utah)
John McCain (Arizona)
Jerry Moran (Kansas)
Lisa Murkowski (Alaska)
Rand Paul (Kentucky)
Rob Portman (Ohio)
Marco Rubio (Florida)
Tim Scott (South Carolina)
Richard Shelby (Alabama)
John Thune (South Dakota)
Pat Toomey (Pennsylvania)
David Vitter (Louisiana)
Up for Re-Election in 2016
DEMOCRATS
Michael Bennet (Colorado)
Richard Blumenthal (Connecticut)
Barbara Boxer (California) retiring in 2016
Patrick Leahy (Vermont)
Barbara Mikulski (Maryland)
Patty Murray (Washington)
Harry Reid (Nevada)
Brian Schatz (Hawaii)
Charles Schumer (New York)
Ron Wyden (Oregon)
REPUBLICANS
Kelly Ayotte (New Hampshire)
Roy Blunt (Missouri)
John Boozman (Arkansas)
Richard Burr (North Carolina)
Dan Coats (Indiana)
Mike Crapo (Idaho)
Chuck Grassley (Iowa)
John Hoeven (North Dakota)
Johnny Isakson (Georgia)
Ron Johnson (Wisconsin)
Mark Kirk (Illinois)
James Lankford (Oklahoma)
Mike Lee (Utah)
John McCain (Arizona)
Jerry Moran (Kansas)
Lisa Murkowski (Alaska)
Rand Paul (Kentucky)
Rob Portman (Ohio)
Marco Rubio (Florida)
Tim Scott (South Carolina)
Richard Shelby (Alabama)
John Thune (South Dakota)
Pat Toomey (Pennsylvania)
David Vitter (Louisiana)
Up for Re-Election in 2016