An internal poll released by Sen. Bernie Sanders Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE's (I-Vt.) presidential campaign shows the senator with wide leads in a matchup with President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE in three states that were key to Trump's 2016 victory.

Sanders leads Trump by 10 points in Wisconsin and by 11 points in Michigan in a head-to-head matchup, according to the data, and he leads by 8 points in Pennsylvania. The polling did not include any of the rest of the varied Democratic field versus Trump, nor did it factor in the possibility of a third-party candidate such as Starbucks founder Howard Schultz, who has implied he will mount an independent bid if Sanders is the Democratic nominee.

ADVERTISEMENT

“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,” Sanders's pollster, Ben Tulchin, told NBC News. “I don’t think any other candidate is as well positioned as Bernie is in these three states.”

Tulchin pointed to data indicating that in all three states a majority of voters believe the country is on the wrong track, disapprove of Trump’s performance and support "Medicare for All," one of Sanders's signature policy proposals. Trump was the first Republican candidate to win any of those states since 1988.

Sanders's campaign has targeted longtime Democratic strongholds in the Midwest that voted for Trump in 2016, accusing Trump of betraying the working class.

“The biggest lie was that he was going to stand up for working families and take on the establishment,” Sanders said of Trump in a Pittsburgh speech this month. “That was a monstrous lie.”

Sanders has repeatedly polled at the top of the crowded Democratic field in other surveys.