Richard Lugar was on “Face the Nation” yesterday and was hardly enthusiastic with his support for the man who defeated him in the Indiana Senate primary, Richard Mourdock.

I’m not convinced that Lugar’s willingness to campaign for Mourdock will make much difference in the Senate race there — odds are that Mourdock will win either way, and if he does get himself in trouble campaigning, I don’t see strong evidence that Lugar could bail him out.

On the other hand, there’s still several months left of voting in the Senate, including the key post-election lame duck session, and it’s hard to know how much loyalty Lugar is going to feel he owes the Republican Party.

Now, I don’t want to press this too far; Lugar has never done anything to make me believe he’s a closet liberal who just couldn’t vote that way because of his party responsibilities. However, we already had a couple of test votes that were worth noting. Lugar voted for three nominees since the primary: new 9th Circuit Judge Paul Watford and both Federal Reserve Board appointees.

The interesting thing is that the last time there was a closely divided vote on a nomination, Lugar was on the other side; he voted against District Judge Miranda Du, who was confirmed by a 59 to 39 vote. So was Sen. Olympia Snowe, although that vote came after her decision to retire at the end of this Congress; Snowe voted yes on Watford and the Fed nominees.

Again, I don’t expect Lugar to suddenly vote like Sen. Chuck Schumer or Sen. Barbara Boxer. But I do think it’s worth watching how he and Snowe and the other retiring Republican senators act over the next few months.

If it’s true that Republicans have been focused on primary elections and Democrats on general elections, it would follow that both Democratic and Republican senators no longer worrying about electoral incentives would tend to act somewhat more liberal than they had previously voted. And that could potentially make a difference on some Senate votes, including perhaps some of those still-stalled judicial nominations.