Doug Schoen: Second Democratic debate -- Two big winners, two big losers and one big, unanswered question

Former Vice President Joe Biden dominated the debate stage and weathered the attacks of nine opponents for the Democratic presidential nomination Wednesday night, emerging the clear winner and standing by his promise to not be “overly polite.”

In possibly the most contentious Democratic primary debate thus far, frontrunners Biden and Sen. Kamala Harris of California sparred with each other and the other candidates over the issues of health care, immigration, race relations and climate change.