The inevitable loss-induced "struggle for the soul of the Democratic Party" has already begun. In a New York Times op-ed, The Nation’s Ari Berman has written that liberals should “Boot the Blue Dogs,” suggesting a smaller but more ideologically homogeneous Democratic congressional caucus would be happier, more effective, and more progressive.

I disagree with Berman's argument on substantive grounds—particularly the CliffsNotes version that the Times’ word limit imposed on him—but in addition, isn't this a really weird time to be talking about a purge of Democratic moderates? After all, Republicans are poised to do the job themselves, seizing so many seats that they'll drastically shrink the size of the Congressional Blue Dog Caucus.

How many of these moderates will actually be left after November 2? Currently, there are 54 members of the Blue Dog Coalition in the House. Four of them are retiring, and two others—Brad Ellsworth of Indiana and Charlie Melancon of Lousiana—are running for the Senate. All six of these open seats are very likely to flip to the GOP.

Looking at Nate Silver’s very precise projections of House races, there are 47 incumbent Democrats that he rates as having a better-than-even chance of losing. Of those, 21 are Blue Dogs. If you assume they all do lose, then add in the six open seats, and acknowledge there are likely to be no reinforcements from the tiny Democratic class of 2010, this leaves you with a Blue Dog Coalition of 27 members, exactly half the current number.

With some luck, the numbers could be higher, but they could be a lot lower, too; four more Blue Dogs are rated by Silver as having a 40 to 50 percent chance of losing, and three more make his list of those with a 30 to 40 percent probability of getting booted.

Silver’s entire projection estimates a net loss of 53 seats by Democrats, leaving a House Democratic Caucus of 203 members. In that scenario, a Blue Dog Coalition of 27 members would represent 13 percent of the caucus, as compared to 21 percent today.

In other words, progressives won't have much purging to do. It’s hard to assess the influence that this downsizing would have on the Democratic minority, particularly in a House of Representatives controlled by the most ideologically coherent Republican caucus in history. But talk about “booting the Blue Dogs” seems beside the point—and it might only aid the Republicans who will try to lure Ben Nelson or Joe Lieberman across the line to gain control of the Senate.