Whatever emotions or anxiety Mr. Obama feels as his candidacy draws to a close, he displays little of it, either in public appearances or private conversations with his close advisers. The air of confidence he exudes, which some critics take as arrogance, grew in part out of the primary, when he worked to avoid perceptions that he was weak or not ready.

But now, he is described by friends as feeling as though he has been thoroughly tested and is prepared to take on the job he has spent 22 months fighting for. Still, it is hard for even those closest to Mr. Obama to fathom what these days are precisely like, even for the unflappable — often inscrutable — senator from Illinois.

His world is awash in powerful, conflicting emotions: the realization, presumably, that he may be about to become president; the huge optimism that he has unleashed, evident in the crowds he is drawing (and something he has told aides worries him a bit, given the expectations set for him); the weighty thinking he is gradually giving to how he would staff a government and deal with a transition in such a difficult time. All of this is taking place as a woman who played a large role in raising him, his grandmother, is approaching death.

“ ‘What if I disappoint people?’ ” Valerie Jarrett, a close friend and adviser, recalled Mr. Obama asking at several points throughout the campaign. “That’s what gives him the energy to keep getting up every day.”

It has been months since Mr. Obama has ventured with any regularity to the back of his plane where the journalists sit. (The one time he played the board game “Taboo” on a cross-country flight to Oregon is a distant memory.) A reporter shouted to Mr. Obama on Sunday as he climbed the steps of his airplane here, headed for Ohio, to ask why Mr. Obama had not held a news conference in weeks.

“I will,” Mr. Obama said. “On Wednesday.”

On a final weekend pass through electoral battlegrounds that spanned three time zones, the electoral climate and his campaign organization provide him the luxury of focusing on states that favored the Republican ticket four years ago. But when his Democratic crowds jeer at the mere mention of Senator John McCain, he offers a gentle scolding, “You don’t need to boo, you just need to vote.”