Benjy Sarlin had the smart idea to call up potential challenge to conservative-leaning Democrats and ask them if they'd try a bit of the ol' Lamont-Lieberman civil warfare. Answer: No. No progressives pose threats to Ben Nelson, Joe Manchin, or (really only on the list because of his DREAM vote) Jon Tester.
All three of these conservative-leaning Democrats are missing the most important ingredient that made Lieberman so vulnerable on his left flank—a solid blue-state electorate. The base is far more likely to put up with a less-than-ideal candidate so long as they have the best chance of keeping Republicans from taking over.
This seems correct. The 2006 race in Connecticut was truly special; Republicans, assuming Lieberman would walk to another term, stuck with a schlub of a candidate named Alan Schlesinger, and if Lamont had not faced an independent challenge from Lieberman he would have likely won a landslide. There was some stupid punditry at the time about what Lamont's victory would do to national Democrats -- make them look hopelessly lefty! -- but he was running on an anti-war platform that appealed. According to the 2006 exit poll , 66 percent of Connecticut voters opposed the war in Iraq. Lieberman survived, in part, because he pretended to support an end to the war, too, and won 38 percent of anti-war voters. (By contrast, Lamont won 8 percent of pro-war voters.)
There is simply no issue as galvanizing to the left right now as the war was in 2006. Progressive groups holler about various causes, and they should, but bursts of outrage about Gitmo or the tax deal are not comparable to a war that most Democrats, and eventually most voters, believed they were lied into. Thus: No more Liebermans.