Netanyahu promoted Avigdor Lieberman from a thud, a night club bouncer, to the most powerful man in Israel. Netanyahu did this so that he alone could be the "head of Goverment" of Israel once again. That he is not the real head of government Lieberman proved with his speech at the UN. All that Netanyahu could do in response was grovel. Lieberman is not 'key' to anything. He has proven in the last week that he is the true 'head of government' in Israel and that Netanyahu is his supplicant.
U.S. confirms ISIS computer expert killed in air strike (Reuters)
from the article: Lieberman 'key' to cabinet vote on settlement freeze