David Gergen : Debate may represent Romney 's last big chance to turn around the race . Comment: Moreover , a big Obama victory would keep the Senate safely in Democratic hands and -- less likely -- might put a few House seats in play . Obama needs a big victory to claim broad support for his plans for second term , Gergen says .
David Gergen : Debate may represent Romney 's last big chance to turn around the race . Comment: Obama needs a big victory to claim broad support for his plans for second term , Gergen says .