The polls need to swing towards Trump by roughly 6.6 percentage points (implying national polling in favor of Biden by 2.6 percentage points), allowing Trump to take Minnesota, Wisconsin, Pennsylvania, Arizona, North Carolina, Ohio, Georgia, Iowa and Texas (but not Florida, New Hampshire, Nevada or Michigan) for Trump to win the electoral college, according to the FiveThirtyEight blog.
Overall — assuming that states that haven’t been polled go the same way as they did in 2016 — Biden leads in states worth 368 electoral votes, while Trump leads in states totalling 170 electoral votes.
But a potential problem for Biden is that Trump could have an Electoral College advantage if the election tightens. Biden currently leads Trump by “only” 6.6 points in the current tipping-point state, Minnesota, but this is narrower than Biden’s 9.2-point lead in the national polls.
* * *
Polling aggregation at Real Clear Politics largely confirms this assessment.
New Mexico Biden + 11.0
Virginia Biden + 11.0
Minnesota Biden + 10.5
Colorado Biden + 10.0 (August 2019)
Maine Biden +10 (no CD breakdown, ignores old polls).
Michigan Biden + 8.0
New Hampshire Biden + 4.3
Nevada Biden + 4.0
Ohio Trump +0.5
Iowa Trump + 1.5
Texas Trump + 1.5
Georgia Trump + 7.5
South Carolina Trump + 12.0 (ignores old poll)
National Biden + 10.1
Betting Odds Biden 56.8% Trump 36.8%.
* * *
Cook's Political Report leans far to the right of FiveThirtyEight in its predictions, but the trends still aren't good for Trump in its June 2020 assessment.
This means there are 248 Electoral votes in the Lean to Solid Democratic category and 204 Electoral votes in Lean to Solid Republican. There are 86 Electoral votes in Toss Up.
To win the Electoral College, Biden needs 22 of the 86 votes in its "toss up" category. This would be Florida, or any two of the other four "toss up" states in their assessment.
Trump needs 66 of the 86 votes in its "toss up" category. Thus, he needs four out of five "toss up" states, one of which must be Florida (and also Ohio, Iowa, Georgia and Texas), to win.
Let's recall how many Electoral College votes some of these swing states have:
New Hampshire (4)
North Carolina (15)
The states that Cook's rates as "Lean R" are polling 0.7 percentage points for Trump to 2.7 points for Biden and are really the "toss up" states that are in statistical ties.
The states that Cook's rates as "toss up" are polling 3.0 to 6.9 percentage points for Biden and are really "Leans D" states.
The states that Cook's rates "Leans D" are polling 6.6 to 10.2 percentage points for Biden and are really "Likely D" states.
There are some modest differences in how FiveThirtyEight and Cook's rank the states relative to each other. Cook's thinks Maine, Michigan and Florida are a bit more Trump leaning than FiveThirtyEight does relative to other states. But, there aren't huge differences in their rankings of the relative competitiveness of the swing states in 2020.