Why Florida may have a big role in 2020

But when you look at the electoral math, it's pretty clear that former Vice President Joe Biden would be wise to look beyond those states and make a heavy investment in Florida.

Florida was a very close state in 2016. Trump won it by just 1.2 points, which is not significantly wider than the margins he won Michigan (0.2 points), Pennsylvania (0.7 points) and Wisconsin (0.8 points). The next closest state (Arizona) featured a significantly larger Trump win (3.5 points). In fact, the presidential margin in Florida has been within 6 points in every election since 1992, including when Democrat Barack Obama won it in 2008 and 2012. No other state has been within that range for so long.

The polling in 2020 makes Florida look like it will be close again. Biden holds a three-point advantage in the Sunshine State in an average of nonpartisan probability polls that controls for pollster. That's closer than Wisconsin (one-point Biden lead), and the same as what we see as in Pennsylvania. Biden is up four points in Arizona and five points in Michigan. (North Carolina, another close Trump won state in 2016, gives Biden a one-point edge, but the high quality polling there has been limited.)

Without knowing anything else, Florida would seem like a good investment for Biden. If the polling is to be believed, it's at least as good as Pennsylvania and Wisconsin.

What makes Florida so enticing among these states is that it has 29 electoral votes. For Biden to win, he needs to pick up 38 electoral votes compared to Hillary Clinton. Florida gets him more than halfway there. Biden cannot win by merely picking up Arizona (11 electoral votes) and Michigan (16 electoral votes). Indeed, Biden almost certainly would need to win at least three of the other states, if he doesn't win Florida. Biden would only need to win two of five states (Florida plus one other) if he carries Florida.

More than that, Florida diversifies the types of states Biden would be competing hard in. When you want to give yourself as many electoral pathways as possible, you want states that are demographically and geographically diverse from each other. That way, if you underperform in one state, it doesn't mean you have in the others. Florida has more nonwhite voters than any of the other close states Trump won in 2016. And it's a southeastern state, unlike Arizona, Michigan, Pennsylvania or Wisconsin. There's really no other state like it.

Florida is the type of state where you'd expect Biden to outperform Clinton given the recent polling. It has the highest percentage of seniors in the country amongst its citizen voting age population. Right now, Biden actually leads Trump among those 65 years and older by nine points in an average of the five most recent probability national polls.

Now, there is a cautionary tale in the 2018 midterms. In Florida, Democrats lost the Senate and governor's race. They won at least one of those in all the other four close states. Moreover, Democrats only won the statewide cumulative House vote by a point, which is more than five points worse than they did nationally.

According to an analysis by the New York Times' Nate Cohn, however, the southern swing state voters who didn't cast a ballot in 2018 were much more friendly to Democrats than those in the northern swing states. In the sunbelt, a large portion were nonwhite. In the north, the clear plurality were whites without a college degree.

With presidential year turnout, Biden's likely going to be very competitive in Florida. If he wins there, it'll be awfully tough for Trump to beat him nationally.