Atrios reads this post about Connecticut election law and agrees that if Joe Lieberman loses a primary challenge, he can't possibly get on the ballot for reelection to the Senate as an independent:
... independent candidates have to submit petitions by August 9th, 2006. It just so happens that the Connecticut primary is on August 8th. In other words, if Joe loses the primary, in order to run as an independent in the general, he'd have to file petitions the very next day.
This is all but a literal impossibility. Joe would have to collect petitions while still runing in the Dem primary. Can you imagine such a spectacle? It would be beyond unheard of for a sitting senator to do such a thing. The only real way Lieberman could run as an indie would be if he abandoned the Democratic Party (save your jokes) well in advance of the primary. Otherwise, he's just talking smack. If he loses the primary, he's done, finished, tostada del dia.
I completely disagree. If you think a popular incumbent can't make dodgy plans of this kind (and yes, alas, Lieberman is still quite popular in his home state), let me remind you that Lloyd Bentsen, who was still well liked in Texas at the time, ran for VP in 1988 while also seeking reelection to his Senate seat. Everyone in the state clearly knew what he was doing and he won the Senate race anyway (with nearly 60% of the vote). I don't know what he had to do to get on the ballot twice in Texas in the same year, but nobody stopped him.
(UPDATE: Commenter gpb reminds me that Lieberman himself ran for Senate and VP simultaneously, in 2000 -- and LBJ also ran for both in 1960.)
Why couldn't Lieberman run a petition campaign? Republicans and (significantly) independents in Connecticut like him a lot. He can turn the negative into a positive by claiming that this is something being forced on him by those unhinged Deaniac Michael Moore Cindy Sheehan Ward Churchill Stalinist-blogger liberals. He'll get great press for that. He'll tell his sob story at every opportunity. His pal Don Imus will nod sagely in agreement.
I'm not saying it wouldn't be wonderful to drive Lieberman out of the Senate and replace him with a genuine Democrat -- of course it would. I'm just saying that he can get away with making contingency plans if he thinks he might lose a primary, so a primary loss probably won't end his race.