The best you can do here is set 'bind policy soft' ldap conf.
Also
enable your chkconfig nscd on. If you are going to do ldap auth make
sure you have an LDAP cluster/farm and a load balancer or some high
availability systems. Things go pretty bad when your LDAP server is
down.
Yes, we actually just tested this with it set to "soft" and it solved
the problem. We do plan to load balance to multiple servers when this
goes to production. I just wanted to make sure that local accounts
could still log in while we transition over, even if LDAP is down.