Inside the White House and out, advisers and associates have noted subtle but palpable changes in Mr. Obama since his re-election. “He even carries himself a little bit differently,” said one confidant who, like others, asked not to be identified discussing the president. He is relaxed, more voluble and even more confident than usual, these people say, freer to drop profanities or dismiss others’ ideas — enough that even some supporters fear the potential for hubris.

A man who attended a meeting in December between Mr. Obama and business executives was struck by the contrast with a tense and perfunctory session months before the president was re-elected. “To say he was a different person is too strong, but he was someone who has won a second term and isn’t going to run again,” said the man, a Republican. “This was a relaxed, engaged president who very genuinely wanted to connect.”…

“Obama is feeling his oats,” said Donald A. Baer, a former aide to President Bill Clinton and now the chief executive of the communications firm Burson-Marsteller.

“I think he probably believes he was cautious and hemmed in by one thing or another in the first term, and he’s decided he’s going to do more of what he really wants and be who he really is in the second term,” Mr. Baer said.