if Ehud Barak and the Labour party walk out of this coalition government, PM Netanyahu will lose the major champions of Israeli statesmen (by that the founding establishment and credible officials) and will have to call a new election - only to lose to both Kadima and Labour. The best bet for the Quartet now is for this existing government, difficult as it is, to make a decisive step towards the peace process, eg. propose the borders for the Palestinians. Ehud Barak does not deserve to take all the flak because he does not represent those elected officials who have substantial negative sentiments on the whole towards the peace process - Lieberman, Begin, Ya'alon, Shas members, etc. Furthermore, the relations between an Israeli PM and a foreign minister and/or defense minister are not the same dynamics or level of commitment imbued as that towards other foreign officials. So the real picture here is not accurately captured probably and only Netanyahu and Barak are privy to that.
from the article: U.S. officials: Barak 'deceived' us about his role in peace process