Just four states are likely to determine the outcome in 2020. Each flipped to the Republicans in 2016, but President Trump won each by only a percentage point or less. The four are Pennsylvania, Michigan, Wisconsin and Florida. Many analysts point to Wisconsin as the single state upon which the election could turn…

The electoral college combinations all begin with Florida and then move to the upper Midwest. One scenario not out of the realm of possibility would produce a 270-268 victory for Trump, but only if he again secures one of Maine’s four electoral votes.

If Trump were to win Florida again, Democrats would need to recapture all three of the northern states — or find substitutes — to win the White House. If Democrats could win Florida, any one of the three in the upper Midwest would give them the White House, unless Trump can put something else in his column.

The three northern states were part of a group of 18 states and the District that had voted for the Democratic nominee in every election between 1992 and 2012, what Democrats believed constituted a “blue wall” of resistance to repeated incursions by Republican nominees.