Clinton made those efforts during the primary, when she spoke with coal miners in West Virginia. While she didn't change every mind and lost the primary in that state, she did manage to change some minds, he told "Power Lunch."
"You've got to relate to people, you've got to ask people for their votes. We didn't ask that group for their votes. We just assumed they wouldn't vote or they were going to vote for Trump. Ask people for their votes. Give them a reason to think that you care about them," Rendell said.
Meanwhile, President-elect Donald Trump was able to tap into the working class' frustration and anger about the economy, he said.
"They needed simple answers, someone to blame. And Donald Trump conveniently said trade was to blame," he said. "They were a convenient group for a good, simple message delivered directly and Trump did a great job delivering that message."
Joan Williams, director of the Center for WorkLife Law at the University of California Hastings College of Law, believes there is an important culture gap between the white working class and many in the Democratic Party who see themselves as progressive.
For example, Democrats try to connect with the working class by talking about things like paid leave and minimum wage. However, the white working class doesn't want to be earning a higher hourly wage working at McDonald's, she said.
"They want a solid job that delivers a solid middle class living, in a context where that's becoming more and difficult but not impossible," Williams noted. "But they don't want to go to college and become anthropologists. And I think sometimes the progressive Democrats forget that."
She also believes many in the white working class resent professionals because they feel professionals look down on them. However, they admire the rich because that's what they would like to be, she said.
"They just want to be exactly the way they are with more money and that's, I think, part of the attraction to Trump," Williams explained.