VP Biden's son Beau: My dad is most effective person to speak to middle class & reassure them President Obama 'has their back'

It was an emotional night for Vice President Joe Biden last night, when the convention moved to nominate him for a second term.

The vice president's son, Delaware State Attorney General Beau Biden, explains to Soledad O'Brien on "Starting Point" why it was such an emotional moment.

"The whole convention seemed more emotional to me," he says. "We had a great energy obviously in 2008. It was a bit of a whirlwind for our family."

"My mom rebuilt our family," Beau adds, referring to the car accident in 1972 that took the lives of his mother and a younger sister. "That's why my dad spent so much time talking about my mom, who he's incredibly proud of."

When asked about his dad being criticized for some things he's said in the past, Beau says it simply means he's hitting a nerve.

"They wouldn't be howling as much as they are, the other side, if my dad wasn't scoring points on Mitt Romney," he says. "They're attacking him because they know he's the most effective person to speak to the middle class and connect with the middle class, and make sure that the American people know that the president has their back."