Will the Covid crisis sink Trump?
In some discussion, I have seen it become almost an assumption that the economic meltdown and the Covid crisis will erode confidence in the President and settle the election, presuming things continue to November as they likely will. Historical patterns suggest that Presidents with good economies and stock markets get elected, those without them don't. We're seeing economic meltdown, high unemployment, fear and more.
However, we don't see this in the data yet. While I normally advise you to disregard all national polls (and I still do -- Clinton has great national poll numbers in 2016 after all) you can look at wide trends in them. I plotted all Biden vs. Trump polls from pollsters rated A/B or better on 538.
Here we see that Biden's margins over Trump, while always positive, have not been improving and possibly are in decline, including into March when we start seeing the effect of the crisis. Presidential Approval polls, also national and thus low value, show only a slight decline of about 0.7% in March. A large fraction of polled voters state they approve of how well Trump is handling the virus crisis.
As always, we must look to swing state polls for the real data, though again they only talk about what happens if the election is held today. And for that, they say that Trump probably wins. See all those swing state polls in my spreadsheet which I continue to update.