Principles have no place in the voting booth. Voting is not a statement of principle. It is a naked political act which should be aimed at achieving an objective. In this case, the objective was keeping the Senate Republican.
To be sure, principles do have a role in choosing the objective. But once the ballots are printed, it's hold your nose and cast the vote most likely to achieve the objective.
What kind of “principles” punishes a guy for being provably libeled?
With “principles” like that, who needs corruption?