• Here’s my interpretation:

      Trump is by far the most popular figure within the Republican Party. Among Republican voters, he is bounds ahead of any other potential candidate. Republicans are also aware that of the primary candidates Trump is probably the most disliked among general voters. Because of the number of people who would vote just so they could vote against Trump, having him as the candidate is a major risk.

      On the other side, Joe Biden is not the first choice of almost any voter who themselves would prefer a different figure to run. Although Biden has certainly gotten some progressive things accomplished as president, Biden has always worked to appeal to the center and markets himself conservatively in many ways. In today’s troubled environment, making compromises on solutions to the troubles including agreeing to not work on some solutions at all is not well liked by the base, and doesn’t offer much to excite those outside of the base. Among the general population there is less excitement for more Biden than there is fear of more Trump.