Najib has the support of MT and the Ketua Bahagian, the support from prime media and so call a group of mangling in PMO office. Najib has the resource as a PM and President of Umno, might against Dr Mahathir in term of war paraphernalia, and based of that, he can win the war, but he will lost the battle. No point winning the war, if you lost the battle.
In GE13, in fact, Bn lost the battle, winning the war, despite having 133 seats in parliament later 134, but lost the popular votes.
This will happened, if war within Umno prolongs, i.e. attacking Tun Daim and Tun Dr Mahathir as a way to shut them up. In Bn, losing a battle, means losing Putrajaya. Najib as a commander, should step in to put a stop , act as a commander of the party and nation.
Najib should emulate whatever move that end in internal fighting, because Umno no longer could handle. Umno today not as strong years ago.