Moon, Pennsylvania (CNN) Joe Biden, campaigning for Democrat Conor Lamb ahead of the House special election here next week, laid out a path for his party to win back the working-class voters who rejected them in 2016.

In doing so Tuesday, the former Vice President offered a glimpse of how he'd approach 2020 if he runs for president again: by working to rebuild a Democratic coalition that includes white, rural, blue-collar voters.

That approach starts in districts like Pennsylvania's 18th, where there is currently a closely watched contest taking place between Lamb and Republican state Rep. Rick Saccone, who is backed by President Donald Trump. The district votes heavily Republican; Trump beat Hillary Clinton here by 20 points in 2016. But there are actually more voters registered as a Democrats.

"The suburbs, the exurbs, the smaller towns -- they got hit pretty hard," Biden said Tuesday at Robert Morris University, where he led a get-out-the-vote rally.

He said Republicans "talk about caring about" and offering solutions for those regions, "but they're not doing any of it."

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