Hypothetically she will need a white old man, preferably a governor from a mild blue state.
Problem is there aren't any.
Phil Murphy comes to mind but republicans came awfully close for the New Jersey governorship.
Polis is too young.
Inslee is too vulnerable to attack due to Seattle.
I wouldn't touch an Illinois governor just for the chances he gets a criminal record.
So that leaves white old senators from states republicans can't hope to win races in, like Blumenthal.
How about Tim Walz? Not that old, would be 64 in 2028*, but a two term governor of a purpleish state who also spent 12 years in the House.
* I am assuming a Harris run would be in 2028 because Biden is 99% likely to be the 2024 Dem candidate.