Sen. Bernie Sanders, I-Vt., leads President Donald Trump in hypothetical matchups in three states that proved critical for Trump's 2016 victory, NBC News reported.

The internal polling conducted by the Sanders team showed 52% of likely voters in Michigan inclined to back Sanders in the 2020 general election, compared with 41% for Trump, the news outlet reported.

In Wisconsin, 52% of voters said they would back Sanders, while 42% said they would vote for Trump. In Pennsylvania, 51% of likely voters said they would support Sanders, while 43% would vote for Trump.

All three swing states solidified Trump's victory over Hillary Clinton in the 2016 election.

"I don't think it's any generic Democrat fits the mold here," Sanders pollster Ben Tulchin told NBC News. "Trump is vulnerable here, but it has to be for the right kind of Democrat who has real strengths and can win these three states."

"I don't think any other candidate is as well positioned as Bernie is in these three states," Tulchin said.

The poll's margin of error is plus or minus 4.9 percentage points.