Email controversy erodes trust in Hillary Clinton

NBC's Kristen Welker notes how Hillary Clinton's email controversy is "becoming a big political problem."

"Everytime she wants to be talking about one of her policies, it's overshadowed by more questions about her use of a private email account while she was secretary of state.

"If you look at the polls, though, the polls do show that the email issue has helped to erode some of the public's trust in her," Welker said.