Karl Rove’s Wednesday Wall Street Journal op-ed centered on the theme of optimal criteria that a potential Vice Presidential running mate should meet in order to be effective should that person be selected as the ticket’s VP candidate. The subheadline of his piece set the tone:

Running mates don’t matter much, but they should be prepared to fill the top office.

Rove expanded on that, conclusively, toward the end of his piece:

Really though, there’s one criterion that matters: whether Mr Trump’s choice reinforces the voters’ perception that he would be a strong, effective president.

Vice Presidents actually do matter, very much, especially in a closely divided Senate. VP Pence cast a potful of Senate tie-breaking votes, and he was effective in shepherding many aspects of Trump’s agenda through Congress. VP Harris has cast a potful of Senate tie-breaking votes in support of Biden’s agenda.

Part of being a strong, effective President is having a Vice President who can be relied on in that sort of crunch.