CLEAN : Trump says 'surprised' at Biden's pick of 'poorly' performing Harris

The speaker discusses their surprise at a particular selection, noting that the individual performed poorly in the primaries compared to others. The primaries are likened to a poll, suggesting that the selection was unexpected given the individual's previous performance.

What can be inferred about the expectations of the individual mentioned in the text?

What does the phrase 'that's like a poll' suggest about the primaries?