I doubt Democratic Senate candidates/incumbent Senators will underperform if it means Kamala Harris will overperforms.

The more likely scenarios are as follows:

1) Harris overperforms and Senate candidates/incumbents get a boost from this.

2) Harris underperforms and Senate candidates/incumbents underperform.

It’s hard for me to understand how Senate candidates/incumbents polling wider than Harris will underperform in this likely high turnout election.