Is the Left tying Iffy's hands on the gun registry?

Liberal Leader Michael Ignatieff's major and public flip-flop, denying a free vote on the Private Member's bill on the gun registry, has got a lot of people talking, with many people trying to make any sense whatsoever of why he made this seemingly politically suicidal move.

So I've been thinking about it more, and came across this article today, entitled "A gun to the heads of the Liberal caucus". While there's nothing new and revealing in the article, it did prompt a new thought, one which appears to fit what few facts we have on the decision. The one question that arose in my mind was prompted by the title itself... and I wondered to myself, "Exactly who's head is the gun pointed at?". (which was then followed up with another question... "And is the "gun" a registered long gun, or an unregistered hand gun?")

Perhaps the Liberal "leader" was finally given an ultimatum from the left wing of his caucus, an ultimatum which he simply could no longer refuse. "Whip the vote on the gun registry, OR ELSE WE'LL 'DION' YOUR LEADERSHIP."

If such a theory is correct, it would then lead us to consider a much larger question... who's really in charge over there in the Liberal Party of Canada? The right-leaning Ignatieff, or the a ultra left-leaning members of his caucus?