You call Lieberman a "northeaterns liberal"? Northeastern, yeah, but liberal???
Liebermann is economically liberal. Granted that he is far more conservative than the others, but he is still liberal when compared to the rest of the country.
Lieberman is fiscally moderate.
He gets liberals riled because he believes that the private sector is the primary engine of economic growth, and has supported cuts in the capital gains tax.
He would repeal tax cuts for the wealthiest 2% only, and use that money to finance additional tax breaks that are of greatest concern to the middle class, e.g. elder care and retirement.
