(CNN) It's way too early to know who is going to win the 2020 presidential race. We don't know who the Democratic nominee will be, and we don't know what President Donald Trump's approval rating will be.

Still, we can look for patterns in the early polling to see what is driving voter preferences. Specifically, are the early patterns for this election looking like 2016 when Trump was able to win a substantial portion of voters who didn't like him? Or is it more like 2018, when Trump's approval rating was very predictive of vote choice for House races?

Our CNN poll suggests that, at least against Joe Biden, the Democrats' best known and most likely nominee, it looks like 2018. That is, feelings about Trump are strongly correlated with their voting preferences.

And that spells potential disaster for Trump.

Voter selection in the Biden/Trump matchup is nearly perfectly predicted by approval of Trump. Among those who approve of Trump, Trump leads 92% to 5%. Among those who disapprove of Trump, Biden is ahead 95% to 3%.

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