Tenant who is moving out because they are buying a house

[Dan Dressler]

I have a tenant who told me that they are pretty far along in the process of buying a house and they would be settling on April 27.  I restated what the lease said as far as breaking it and started my search for new tenants.  

After finding a husband and wife who want to move in, but have not signed a lease yet, the original tenants told me that there was an issue with the sale (liens against the property) and no longer want to move out, but they are still trying to get the liens cleared up.

What would you do in this situation?  I am fine with them paying the penalty and moving out, but don't want to keep going back and forth with them and any prospective tenants.  

Any advice is appreciated.