Glenn Greenwald has an excellent post up on Lieberman's radically neoconservative stance on Iran, which is actually more unilateral than - and to the right of - the Bush Administration's:

Joe Lieberman is a neoconservative whose foreign policy philosophy is inevitably going to lead him to support whatever hard-line policies against Iran which this administration wants, including a military attack. To the extent Lieberman is willing to deviate at all from the administration's Iran policy, he will likely be more hard-line than they are, just as was the case with the Santorum legislation.

It would be incredibly irresponsible for the Democrats not to have an all-out debate about whether they want to be represented in the Senate by someone whose foreign policy views are more or less identical to the most militaristic ideologues in the administration. Contrary to the conventional wisdom that the primary challenge against Lieberman is motivated almost exclusively by his support for the Iraq war (an obviously false claim given that numerous Democrats who supported the war are still supported by most Democrats), Lieberman's neoconservative world-view is squarely at odds with the views of most Democrats (and most Americans), and that, among other things, is what is at issue in his primary challenge.

Of course, Lieberman is trying to out-hawk Dick Cheney on Iran at the same time that Iran's president is warming to negotiations.

This is exactly why Iraq is not just "a single issue" in this race. It's about whether our representatives, like Sen. Lieberman, let their zealous ideological beliefs blind them to the disastrous consequences of their actions, and whether we can trust their judgment on decisions where the lives of thousands of Americans and countless others hang in the balance.

This is a huge issue. And we need Ned Lamont in the senate, because we desperately need sound judgment on decisions like these in the future.