He just did... he has nothing to worry about.
He may not have to worry about his seat, but he really likes being Majority Leader.
Look at the Senate seats up in 2014, then figure that it’ll probably follow the pattern of previous mid term elections that take place during a President’s second term.
Gun control will turn a 50/50 shot at kepping the Senate Dem and turn it intoa serious GOP blowout.
A good approach right now would be to both hammer Obama on being anti Second Amendment while ticking off his own base be accusing him of selling out and caving in to the gun lobby.