State of the presidential race: A deep dive on the polls

The 2016 polling failure was as much about the imbalance between national polls — which were mostly accurate — and a conspicuous lack of rigorously conducted battleground-state polling.

So far, 2020 looks like more of the same.

The pre-convention rush of polls has been almost exclusively at the national level. Most major news organizations have released (or will release) national poll results prior to the start of the Democratic convention on Monday, including the three major broadcast networks, two major newspapers, PBS, NPR and Fox News.

Meanwhile, there has been very little reliable, nonpartisan state polling released over the past week. A Marquette Law School poll in Wisconsin found Biden leading Trump by just 4 points among likely voters, 50 percent to 46 percent — a result that suggests the president is still running stronger than his national standing in at least one key Electoral College state.

The national polls serve an important purpose. They help reveal