PostgreSQL synchronous replication time out?

I’m using PostgreSQL 9.3 with synchronous replication. I have 2 synchronous replicators and 1 async replicator. My problem is when 2 synchronous replicators are down, transaction will wait indefinitely.
I found following discussion about this,

http://postgresql.1045698.n5.nabble.com/Timeout-for-asynchronous-replication-Re-Timeout-and-wait-forever-in-sync-rep-td3293679.html

but could not found a solution. Is there a way to resolve this problem ? ( may be using tool like pg-pool )