Dubbed the "Billification" of Sen. Clinton's campaign by some insiders, Mr. Clinton has become something of a strategist-in-chief in recent weeks. He has been pushing for harder and sharper attacks on Sen. Obama. While she has jabbed her opponent over his "elitist" tone and controversial statements by his former pastor, Mr. Clinton delivers his own slams on the stump, calling Obama ads misleading.

Mr. Clinton has placed several of his own aides at headquarters, including his former lawyer and a bevy of strategists. Known as a bad loser, Mr. Clinton privately buttresses his wife's drive to push on, telling her, according to aides: "We're not quitters."

On his own daily message calls, advisers say, he implores: "We've got to take him on every time." At the Clintons' Washington, D.C., home recently, these people say, he reviewed possible TV spots and told ad makers to be more hard-hitting, faster and harsher.