A defiant Muammar Gaddafi is threatening bloodshed and revenge against protesters, he sounds like a mad man. It seems that even after ruling Libya for 41 years, his desire for power is not satiated. He is willing to destroy Libya rather than accept reality and step down.
The day Hosni Mubarak was ousted, Gaddafi should have initiated an orderly transition to democratic rule. Gaddafi's defiance can only cause more death and destruction resulting possibly in the breakup of Libya. Even if he overcomes the situation momentarily, his game is up and chances of him lasting as a ruler are minimal.
US wielded a great deal of influence with Egyptian military, hence were able to ensure Mubarak's departure, but there is no such connection here. Gaddafi is his own man and does not listen to anyone, so unfortunately there is no one to influence him to make the right decision at this critical juncture.
Let us hope better sense will prevail in the end and Gaddafi will decide to hand power to a new civilian administration.