"They get bitter, they cling to guns or religion or antipathy to people who aren't like them or anti-immigrant sentiment or anti-trade sentiment as a way to explain their frustrations."
This comment was made during the 2008 campaign, but not the general election campaign. It was made in the spring of 2008, and was an attack on Hillary Clinton's supporters. The way the 2008 race was shaping up at the time, Clinton was doing well among white working-class voters while Obama built his campaign on the support of all the misfits who make up the Democrat grassroots. There was an enormous racial angle to this, despite the denials of the Clinton campaign in 2016. Remember -- it was Clinton's team in 2008 who first floated the stories about Barack Obama's mysterious origins.
Fast-forward to 2016, and it's easy to see why Clinton lost. She was forced to go begging for votes among the Obama misfits she had alienated back in 2008, and many of them simply weren't having any of it. It's remarkable that in eight short years Obama effectively handed all of Clinton's white working-class supporters to Donald Trump.
Pennsylvania remembered that quote very well, and with some ... bitterness.