Biden responds to doubts about his age and fitness for office with a combative speech. Analysis: The president flubbed some prepared lines and stumbled a bit during improvisations.
But he disproved the Republican Party's caricature of him as a weakened old man who needs to retire. . By Peter Nicholas - NBC News It's too early to know whether Biden's speech will make a lasting impression on voters who saw it. Biden's challenge Thursday night was "to convince people that he has the strength, the energy, the vigor and the focus"