By Jon Keller

BOSTON (CBS) — For those opposed to an election-eve or lame-duck GOP effort to jam through a successor to the late Supreme Court Justice Ruth Bader Ginsburg, Tuesday’s decision by Sen. Mitt Romney to back a pre-inaugural vote was infuriating. Wrote one moderate viewer: “Every time I put my faith in a Republican they let me down.”

But this power grab – which is fully within the rules of the Senate – is just the latest in a long string of bitterly partisan performances surrounding judicial appointments by both parties.

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And if Romney’s move surprised you, may I respectfully suggest you weren’t paying close enough attention to who Mitt Romney is.

For starters, he’s a conservative when it comes to the judiciary and always has been. When Romney was governor here he touted himself as a reformer interested only in “common sense,” but by the time he left in 2007 he had abandoned judicial reform and made it clear he wanted law and order conservatives on the bench.

Romney also represents a very conservative state these days. So when he said today he supported solidifying conservative control over the Supreme Court, that should surprise no one.

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Romney is a man of principle in his personal life and, at times, in public arena. Consider his explanation of his impeachment conviction vote, which read in part: “The Founders’ decision to invest senators with this obligation rather than leave it to voters was intended to minimize—to the extent possible—the partisan sentiments of the public.”

But the Romney endorsing a fundamentally partisan move that could be left up to voters if he so chose is not Mitt the moralist. It’s Mitt the pol.

In addition to being a conservative, he is also a politician, and an ambitious one. Voters here will remember his willingness to flip-flop on issues, even matters of principle like abortion.

Mitt Romney wants to be president. That’s why he ran for it twice and has been making moves – including his impeachment vote – that could position him as the frontrunner to salvage the party from the potential wreckage this November. Future GOP primary voters might forgive him that impeachment vote four years from now, but would they overlook a “no” vote on securing a conservative majority on the court? Even if it turns out that with other Republicans lining up behind Trump, his would not have been the swing vote to deny confirmation?

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Doubtful. And so another chapter is written in the career of a high-minded man determined not to let his mind get so high that his political career runs out of oxygen.

Jon Keller