Once you get into contract though, your power is the sellers signature on your contract. If the seller receives a backup offer that is better (and the likelyhood that the lender will kick your offer for the better one) your agent has to go to work to cajole the othe buyers number out the the listing agent (which he is under no duty to disclose to you) and give you the opportunity to raise your offer before your time runs out.
This is reason 427 why short sales are such a challenge.
Now to the offer you made on the short sale home. Did the contract that was submitted contain the signatures of both the buyer or seller? If yes, you have an executed contract. Hopefully you did not submit an escrow deposit also. An executed contract does put you in 'first' position. It is possible the offer(s) without signatures, would be bundled and submitted to the bank or service company simultaneously and the bank has the option to pick and choose. This scenerio would not require an excuted contract (no signatures). However, the bank may choose another offer without the obligation of explaining their choice. Each bank or servicing company operates with independant internal guidelines. As a buyer, you are mostly powerless to influence the process at all.
Now, was the list price which you based your offer on, realistic. If the list price was significantly below market value, and the home is free of excessive distress, you have an excellant chance of receiving a counter from the bank or lose the opportunity to purchase this home altogether. This list price on many homes in a short sale situation is nearly irrelevant. If the list price is too good to be true.....well you know the rest. The bank will determine the value, not the home owner or real estate agent. The bank may counter with market value and try to get you to pay off some of the homeowner debt, especially if a second exists.
Short sales is the current wild west of real estate. Too many masks, too many players, way to many long term conseqenses should you have the misfortune to engage the masked land trust.
Best of outcomes with your short sale purchase. You seem to be dealing directly with the homeonwer which is a good situation. Keep us informed of the progression of your purchase.
The best source for this information will be the listing agent. They are responsible for submitting your offer to the bank. I suggest that you have your agent contact the listing agent to inquire if your offer will be submitted to the bank. They can also ask as to how many offers have been received and how those offers will be processed. Your offer could be out bid. The bank can continue to have their agent take further offers and unfortunately even if you submit an offer before anyone else that does not necessarily mean your offer will have priority or will be accepted. Short sales take time and alot of patience. So try not to get yourself to attached and keep looking at more homes. You should also discuss with your agent about putting in multiple offers on back-up properties. Best of luck!