Mrs. Clinton has not given up, in her head or her heart, her quest to return to the White House, advisers say. But as resolute as she is, she no longer exudes the supreme confidence that was her trademark before the first defeat, in Iowa in January. And then there were more humbling blows, aides say: replacing her campaign manager on Feb. 10, then losing the Wisconsin primary and her hold on the women’s vote there last Tuesday.

If she is not temperamentally suited to reckon with the possibility of losing quite yet, advisers say, she is also a cold, hard realist about politics — at some point, she is known to say, someone will win and someone will not.