As a catharsis for myself, I will paraphrase my arguments with due deference to all the Kossack dissenters.  
1. Hesiod makes an important point, one that I made obtusely.. it is too early to accurately poll this race.  After weeks of non-stop media coverage of, and ad saturation by, the "two" senate candidates, we should expect that the GOP candidate would be largely ignored by the poll responders.  It will take a few weeks at least for people to absorb that fact that there are now THREE choices in the senate race.

2.  In a three way race, the Republican on the ballot can expect to pull at least 20% of the vote.  Why?
     First, the GOP candidate has major advantages.  The Governor of Connecticut is a very  popular Republican governor.  That means that Schlesinger, or whoever is the eventual nominee will be placed first on the ballot, as a major party candidate, which makes him appear far more serious than the third party candidates.  Connecticut for Lieberman will be listed 5th on the ballot, after, I believe the Greens and the Libertarians.  
     The GOP must receive the support of the state party, if not the national party.  That means that he will enjoy basking in the positive glow of Governor Rell.  That alone in CT will guarantee at least a 20% showing in the election.  
     Not all voters are bloggers, or high-information voters.  I found this out quickly as I drummed up support for Lamont among family and friends.  Many voters will simply vote for the Republican because they are Republican.  Now, I like to think that Connecticut voters are savvy, and maybe they are a little more than in some of the less civilized states, but I can guarantee that not every GOP voters will become an insider, strategic voter.  Many will, I am sure, but not all but 6%.  
      As I responded with some frustration to a seemingly dense DKos member: "If you are challenging my logic, cite me one example of a major party candidate running for the senate in a state led by a governor of his party who received less than 20% of the vote.  Ever."  (addendum... or shut the fuck up)

3.  The rise in the Republican candidate's poll numbers will come at the expense of Lieberman.  Lieberman is not a Republican, no matter how much the media want to spin this race.  People who have been diligently voting against Lieberman for 18 years or more (at least 34% of the voters) will not vote for Lieberman just because he lost his primary, especially as he promised to caucus with the Democrats.  

Lieberman had made the decision to run as an independent when the primary race promised to be a different game than the one that was played out.  We all expected a low-turnout summer primary, at least through the spring.  I thought that Lamont had a chance to squeek it out, with a low turnout and a mobilized base; this was the conventional wisdom.  And Lieberman thought that was his Achilles Heal.  He said as much to Maura in CT.  But we had a record turn-out and Lieberman still lost.  The justification for forming his narcissistic party has been debunked.

Also, in the early summer primary polls, Lieberman was ahead, but potentially vulnerable to Lamont, but he trounced everyone in a three-way race by huge margins.  With those numbers, forming his own party was his guarantee that he wouldnt slip and fall as a fluke, the mighty Smaug felled by a puny mortal's arrow.  This justification has also been proven bullshit.  

If we get a poll in a couple of weeks that accurately reflects what the GOP candidate will get in the race, and shows Lamont decisively ahead of Lieberman, I think even Joe will get it, and withdraw his bid.