Why Don't Conservatives Support the Libyan War?

Victor Davis Hanson spells out the reasons for opposition:

Why are many conservatives against the Libyan war? Is it, as alleged, political opportunism — given their prior support for the 2001 and 2003 wars in Afghanistan and Iraq?

No. Most of us support wholeheartedly our troops now that we are in, but opposed the intervention for reasons that were clear before we attacked, and are even clearer now. Among them:

1) Timing: If the administration believed this monster should have left, it should have acted when the rebels had the momentum, and not issued threats and demands for Qaddafi to go without commensurate efforts to follow such saber-rattling up. Fairly or not, the administration established a goal that it now seems to be backing away from, as it talks of toning down the operation before it is even a week old. We boasted about storming Vienna, pulled up at its outskirts, froze, and are now bewildered that someone inside actually is fighting back.

2) Approval: To start a third war in the Middle East, the president should have first gone to Congress, especially since he and Vice President Biden have compiled an entire corpus of past speeches, some quite incendiary, equating presidential military intervention without congressional approval with illegality to the point of an impeachable offense (cf. Biden’s warning to Bush over a possible Iran strike). And why boast of U.N. and Arab League approval but not seek the sanction of the U.S. Congress?

That's just the first two - there are five more plus additional explanation. Read it all here.