My friend Patrick Ruffini, as ardent a Republican as I know, wrote last night to make the case that Joe Lieberman as John McCain’s running mate would not be “the worst pick”.  While Lieberman wouldn’t be his first choice, Patrick says that Lieberman could help McCain win, and that his presence on the ticket would essentially be otherwise meaningless.  He claims that Lieberman already boosted McCain into the nomination with his endorsement in the primaries, proving his value:

The difference is that any of the conventional picks don’t help McCain with his #1 priority: winning the election. Despite narrowing the gap, McCain is currently about 3 points behind. He needs a better VP pick than Obama will come up with — and unless Obama chooses Clinton, Obama’s pick will be safe and milquetoast. Lieberman is the most obvious opportunity to shake up the calculus of the race. Picking him did something for Al Gore in 2000, taking him from a sure loser to a position of strength in the fall. A conservative VP on a losing ticket is still a losing ticket.

Lieberman’s endorsement of McCain was a turning point in McCain’s favor in winning the primary. Republican primary voters did not recoil in horror that a Democrat would give McCain his stamp of approval. Much the opposite. It’s very possible someone else would have been the nominee had Lieberman not endorsed. It’s easy to see how McCain would feel a deep sense of gratitude.

Win or lose, Lieberman as the VP nominee would have the practical effect of forcing him to switch parties sooner rather than later. If you want to notch a Senate seat and prevent a filibuster proof Obama majority, this is one way of doing it. As part of the Republican conference, he’d start voting as a party line Republican most of the time, though not always.

Patrick makes a number of mistaken assumptions in this passage, chief among them the idea that Joe Lieberman would somehow become a mostly-party-line Republican in the Senate under any circumstances.  That actually sells Lieberman short as a man of principle.  Lieberman has a well-established record as a liberal Senator throughout his career, with Poole Report ratings that consistently put him on the left side of his caucus.

Does Patrick really think that Lieberman would abandon all of that just because he changed party affiliation?  If that were true, then Lieberman would never have opposed his current party on the most explosive issue in the last few years: the Iraq war.  At best, he’d vote to support the Republican leadership, but otherwise we should expect a voting record to the left of Lincoln Chaffee.

Lieberman’s endorsement did not win John McCain the primary, either.  His friendship with McCain probably hurt him among Republicans as much as it helped among independents voting in GOP primaries.  It certainly lent some heft to the RINO charge, especially since Lieberman’s liberal record is very plain to see.  By the time the official endorsement came on February 3rd, McCain had already won more primaries than his rivals (New Hampshire, South Carolina) and held a slim lead in delegates over Mitt Romney.

The addition of Joe Lieberman will not convince independents that McCain is a maverick; it will convince an already-skeptical GOP base that McCain is a RINO.  Patrick knows better than most how essential enthusiasm is to the GOTV efforts and fundraising.  McCain appears to have finally generated some of that enthusiasm, and picking Lieberman would snuff it out for good.  Republicans respect Lieberman, but they don’t want a liberal Democrat as the person who would succeed to the Presidency if something happened to McCain — which is the entire point of the Vice Presidency.

Lieberman may not be the worst choice, but he’s close to it.  If McCain wants a Democrat, let him pick John Breaux, whose positions really do reflect conservative values.  Otherwise, the Republican Party has plenty of options for a Republican ticket.