Balkenende has to convince the centre to vote for him. And hope that the VVD(Libs) don't implode. But I think the only scenario in which he will survive as PM is that he wins/keeps the same amount of seats while Labour loses seats. It might happen if voters vote Socialist & Green in large numbers instead of Labour. When these parties won't have a majority, and Labour loses (gets smaller than CDA), the CDA-Labour coalition might be the only available option. In this scenario, he might stay PM.