Take a look at your copy of the offer/contract. On the dates & deadlines the last date should be "acceptance date" . That is the date by which they are to respond. If it is a short sale or a bank owned, that date may not be specified or it may be irrelevant. When the banks are involved on the selling side everything takes a long time.
Ask your Realtor to explain and to keep you updated on what the Seller's agent is saying is going on.

Is the house you are offering on a "normal sale"...or is it possibly bank owned or a short sale? Here in AZ there is a acceptance deadline spot in the contract. If the property is bank owned or a short sale you can just throw that out the window, however! :~) Banks are taking any where from 5-7 business days (and even longer) on a bank owned home and on a short sale it's not uncommon for the acceptance to take 30-90 days.

What is your Realtor telling you? God luck!

Your offer should have included an acceptance deadline date. This is the date the seller has to respond to you by.