Kos endorses the Republican in the NY-23 special House election. The reasoning is a mix of two factors: a) the Republican genuinely does seem more liberal than the Democrat (such that there is a "Conservative Party" candidate in the race who is actually competitive with the field), b) overflowing spite towards "blue dog" Democrats, of whom this Democrat would undoubtedly become a part of if elected.
UPDATE: Meanwhile, significant portions of the GOP apparatus are getting behind said Conservative Party candidate over their own nominee. So Democrats are supporting a Republican who they think is more liberal than the Democrat, while Republicans, noting this, are supporting a third-party candidate firmly in tea bag territory, thus throwing the advantage to ... who, exactly? I have no idea.