When Trump closed the gap in the waning days of the 2016 campaign, he had to convince very few Clinton supporters to vote for him. Trump merely had to pick up support from those who were undecided or backing a third party candidate.
Right now, Trump’s road will be difficult if not next to impossible to win if he doesn’t take back voters who are already with Biden.
Other historical examples aren’t too kind to Trump either. The only other challenger at this point who was at or hovering around 50% was Jimmy Carter in 1976. He won.
Here’s the problem for Trump: The average poll at this point had Truman’s Republican opponent Thomas Dewey at 46%. So even as Biden’s advantage over Trump in these polls is less than 2 points greater than Dewey’s was over Truman (just south of 9 points), Biden’s earning about 5 points more support from voters. Dewey simply didn’t have voters committing to him the same way Biden does at this point.
Indeed, Trump’s need to convince those who aren’t already with the other camp is reflected in another way. His disapproval rating in the average poll is 54%. No other president at this point in the polling era had a disapproval rating this high before their chance to win a second term. Truman’s was 47%, as his approval rating languished at 39%. There was, however, a majority of Americans who at least didn’t disapprove of him.
Trump proved in 2016 that he can defy history. If he is to win a second term in 2020, Trump’s going to have to make some.