Four years ago, Trump won election with the lowest favorability for a major party presidential candidate in the polling era. He did so because he won the overwhelming plurality of voters who both disliked Hillary Clinton , the second least liked candidate of all time, and him.

New polling indicates that Trump's low favorability ratings are causing him more electoral difficulty than he should have based on job approval ratings alone.

Trump stands at a negative eight point net favorability (favorable - unfavorable) rating in an average of six recent high quality polls from CNN/SSRS NBC News/Wall Street Journal and Quinnipiac University . Presumptive Democratic presidential nominee Joe Biden's not helping Trump's cause, as his net favorability rating is higher than Trump's in all these polls, and he's winning the overwhelming share of those voters who like neither Trump nor he.

Put simply, Biden's not allowing Trump to turn this into a choice election between two disliked candidates, as it was in 2016

Trump would be in better shape if 2020 revolved around how voters viewed Trump's job performance. Indeed, we usually measure a president's popularity with the public by examining his approval ratings. If you look at an average of the same six polls we looked at above, Trump's net approval among voters (approval - disapproval) stands at negative four points. That's four points higher than his net favorability rating.

You can see it in the swing states as well. Fox News polls released from the swing states of Florida Michigan and Pennsylvania . His net approval rating in the three states averaged negative one point. His net favorability in the three states averaged negative six points.

All of these numbers seem to indicate that the President has a likability deficit. A small, but electorally significant, portion of voters seem to approve of the job he is doing as president, but don't have a favorable view of him.

Now, it would be one thing if this portion of the electorate were making their electoral decisions based on their approval rating solely. That doesn't seem to be happening. Trump's deficit to Biden nationally (six points) is higher than his net approval ratings would suggest alone. In those three swing state polls from Fox News, they match Trump's net favorability rating almost perfectly.

History suggests that come November, Trump should really try to clean up this problem. Using CBS News and NBC News/Wall Street Journal data, I looked at net approval ratings and net favorability ratings of the President in every election since 1980 (i.e. since favorability ratings were regularly asked). I then compared them to the final margins in those elections.

Presidents' net favorability ratings have tended to be more predictive of the outcome. In the six elections in which the incumbent was running for reelection, the president's net favorability differed with the final outcome by four points on average. The election margin differed with the net approval rating by eight points on average. Including all presidential elections (regardless of whether the incumbent was running), the difference rates slid up to six points for net favorability and twelve points for net approval. This seems to suggest that favorability is overall a more important indicator of electoral success than job approval.

Trump perhaps reminds me most of Bill Clinton, the other recent president to be impeached. Like Trump, Clinton had personal foibles. Clinton's net favorability rating trailed his net approval ratings in both his reelection and the 2000 election to determine his successor. Both times, Clinton's net favorability ratings were much more predictive of how his party did in the election.

Now maybe it'll be the case that Trump will prove to be so popular or unpopular that any differences between his approval and favorability ratings won't matter. But in a country that is often divided fairly down the middle, the deficit could mean the difference between winning and losing.