WASHINGTON – Four years ago he was the fifth-youngest president to take the oath of office. Now Barack Obama is 51, his hair more gray, his face more lined.

He's the parent of a teenager and a tween. (Insert your own joke about teens and gray hair here.) His blood pressure has ticked up a bit, although it's still excellent. He's quit smoking. He's a pet owner.

And the changes in the president aren't just physical. As he enters Term Two, he is sounding more confident, vowing a harder line on negotiations, relying more on trusted allies, promising less and expressing more cynicism about the grip of partisanship on Washington.