>> checking in with top sources close to vice president biden, top democratic donors in the country had one question heading into tonight's debate. would biden survive? every other rival coming at him on the iraq war vote. on trade. could he emerge unscathed? he did battered and bruised but he survived. the texts coming in he is carrying on. he embraced the obama mantle and remains for now the front runner. >> democrats secure in their title of maintaining the world's largest circular firing squad? >> you see candidates saying biden is vulnerable. booker had a strong night. they expect him to get a bump. he played the role harris played in the first round. the biden foil. really challenging mr. biden on