Perry Bacon Jr. rounds up recent swing state polling on 538. As the graphic below shows, Biden has been leading in NC, WI, FL, PA and MI in an average of "high-quality" polls. One thing of interested in the extent to which Biden is compressing the gap between national-level polling and swing state results, a gap that was crucial for Trump in 2016.
Previously I covered Harry Enten's analysis suggesting that that was declining. And a recent NBC/Wall Street Journal found Biden leading by 7 points nationally and by 6 points in 11 key states (Arizona, Colorado, Florida, Maine, Michigan, Minnesota, Nevada, New Hampshire, North Carolina, Pennsylvania and Wisconsin), consistent with Enten's analysis.
In Bacon's data we can see the national-state gap being compressed in PA and MI, but looking about the same in FL, WI and NC as it was in 2016. If Biden can move another of these latter states into the no or very small national-state gap, it would insulate him against the dreaded popular vote-electoral vote split in a closer national race. If not, that outcome remains quite possible.
But the other side of what these data indicate, as Bacon points out, is that if Biden keeps his national lead in the current range, he should be pretty safe in the electoral college as well.