Four years ago Barack Obama was a fresh-faced political sensation who had not even served a full term in the Senate and was about to become one of the youngest presidents ever. Now he is 51, his hair more gray, his face more lined.
He's the parent of a teenager and a pre-teen. His blood pressure has ticked up a bit, although it's still excellent. He's quit smoking. He's a dog owner.
The changes in the president aren't just physical. As he enters Term Two, he is also 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.
And perhaps most important, he seems more convinced of a need to keep average Americans with him, coming full circle to his 2008 grassroots campaign.
``You can't change Washington from the inside,'' he said during his re-election campaign. ``You can only change it from the outside.''
On the best days of his presidency, Obama has been witness to the power and possibilities of the office he holds. On the worst, he's seen its limitations.
He has celebrated passage of his transformative health-care overhaul and mourned the children massacred at an elementary school in Newtown, Connecticut.
He has savored the news that Osama bin Laden at last had been brought down. And stood vigil over the remains of fallen soldiers returned to the U.S.
Between the highs and lows came the daily grind of a daunting job whose demands never end. There is always one more negotiation. One more legislative tussle. One more economic soft spot. One more natural disaster.
By all accounts, Obama's style and his character remain largely unchanged. But every chapter of his presidency _ the gasp-inducing early economic crisis, the battle over health care, the midterm congressional shellacking, the mass shootings in the past year, the endless negotiations over debt and deficit, the re-election brawl _ has helped to mold him and to shape his perspective.
``Four years in, he has a very good sense of the job,'' says senior adviser Valerie Jarrett. ``He has a great sense of what is possible if you do have the American people behind you and willing to push with you to make change.''
Change has not come easily in Washington however, which remains as divided as ever. Republicans largely blame Obama's wrong-headed presidential policies and