In the most recent Marquette Law School Wisconsin poll, Biden, who has been running the strongest of tested candidates in the state, was up on Trump by 4 points. That's better than the December poll (a one point advantage) and the November poll (3 point deficit).
What's Trump's Achilles' Heel in the state? I've said it before and I'll say it again: white noncollege women. In a recent Global Strategy Group study, Trump's net approval was +28 among white noncollege men and -2 among white noncollege women. Wow. That's a really big difference. Leverage that difference and the Democratic candidate wins the state.