The Democratic presidential candidates turned on one another in scorching and personal terms in a debate on Wednesday night, with two of the leading candidates, Senator Bernie Sanders and Michael R. Bloomberg, forced onto the defensive repeatedly throughout the evening.
In his first appearance in a presidential debate, Mr. Bloomberg, the former mayor of New York City, struggled from the start to address his past support for stop-and-frisk policing and the allegations he has faced over the years of crude and disrespectful behavior toward women. Time and again, Mr. Bloomberg had obvious difficulty countering criticism that could threaten him in a Democratic Party that counts women and African-Americans among its most important constituencies.