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The ever-growing field of 2020 Democratic presidential candidates grabs most of the headlines, but President Trump's re-election campaign is always lurking right beneath the surface. Axios reports that Trump's team is "already gathering ammunition" against his potential opponents and trying to pinpoint where in the United States the president might be the weakest.

Those places, at this point, appear to be Wisconsin and Michigan.

"The issue for Trump last time was, frankly, he spoke to working class voters and Hillary [Clinton] didn't," one former Trump campaign official told Axios. "So if you take that out of the equation, something like 60 thousand votes in Michigan becomes a lot harder."

The campaign staff isn't too concerned about a few other swing states, though. The gubernatorial races in Florida, Georgia, and Ohio — which all resulted in Republican victories despite strong Democratic candidates — has the Trump team feeling confident. They also aren't worried about Pennsylvania. Per Axios, Clinton campaigned heavily across the state and "won just as many votes in Philly as she could get," and Trump still won.

But would that have to change if former Vice President Joe Biden, who still hasn't officially announced his candidacy, ultimately emerges as the Democratic nominee? Biden has strong Pennsylvania roots; he was born in Scranton, after all. He also represented neighboring Delaware in the Senate.

In fact, an earlier Axios report from July 2018 said that Trump's two major concerns at that time were having to run against Biden and losing Pennsylvania — so the recent about-face on the state is a surprising strategic development.