I honestly hold the pro-LIEberman Republicans directly responsible for the RATs taking control of the Senate in 2006. Even if Ned Lamont had won in CT, a single victory by either George Allen in VA, Jim Talent in MO, or Conrad Burns in MT would have made the difference and resulted in a Republican controlled Senate. All three lost by 1%, but the GOP nationally was too focused on kissing LIEberman's butt to care about those races.
If Republicans who would have given money to Talent, Allen, etc. gave to Lieberman instead, then you’re correct that it hurt us. But had the GOP gone all-in for that loser card-counter with no chance of winning (it would have been miraculous for someone like Schlesinger to get 34% in CT in 2006, and if he somehow got 34% it almost certainly would have been because Lieberman was getting less than 25%, in which case Lamont would have coasted to victory), it would have meant people giving money to Schlesinger *instead of to Talent, Allen, etc.*
When Schlesinger refused to drop out, the GOP’s decision to bail was the correct one. And had I lived in CT at the time,I probably would have voted for Lieberman in order to keep Lamont from winning (just as if I lived in a district in which the GOP has no chance I would try to get the least bad Democrat elected); keeping Lamont out was especially important because of his age, since if Lieberman won again we’d likely have another bite at the apple soon (and we did in 2012, when RINO Linda McMahon managed to blow a second straight winnable race). But I wouldn’t have given Lieberman a dime: I’m pretty sure that the only pro-abortion candidate to whose campaign I’ve ever made a monetary contribution has been Scott Brown in the special election (when I had been informed that he was pro-choice with restrictions, and when the alternative was 20+ years of Coakley), and I’m certain that the only Democrat to whom I’ve ever contributed was socially conservative, economically moderate Democrat Henry Cuellar of TX when he faced a rematch against moonbat Ciro Rodriguez in the Democrat primary in a district that the GOP wasn’t even contesting.