Most likely they will not accept your counter offer since they already opened escrow.
Have your agent talk to the listing agent and see if they can keep your counter as a backup offer.
Jes Sierra, B.Sc.
Century 21 Beachside RealtorsÂ®
Chino Hills, CA
If this is a short sale or REO you might have a chance. Most Short Sale or REO lenders are letting their agents know to continue marketing for offers in this markets "distressed atmosphere". I would recommend coming in with cash or a pre-approval(not a pre-qualification).