If Obama nominated Governor Sandoval, he is not nominating anything close to a conservative. Sandoval is a classic RINO.
That being said, Obama could set a trap, for the GOP and nominate someone palatable to them and they could schedule hearings on that nominee. Obama could then easily withdraw that nomination and throw in the most liberal candidate he could find.
The GOP would then be left looking like not holding a hearing on that candidate was pure politics.
They are better off refusing to hold hearing on any Obama nominee.