Currently, the US Senate is split 50-50. If something should happen and one of the Senators die or resign, it's possible that they are replaced by a new Senator from the opposite party, giving one side a 51-49 advantage, and thereby taking full control of the Senate.

Which current Senators fall into this category? That is, which Senators come from a state where the governor is of a different party and has the authority to appoint whomever they want to an empty Senate seat?