You can if your mortgage professional can send the loan to another lender. Wholesale lenders that service brokers have what they call "fall out rates". If the broker locks a loan and then doesn't close the broker risks being cut from being able to use the lenders programs at all. No one I know is willing to do this in this market. Lending sources are drying up everywhere. You have to respect the people that are working hard for you. There are no guarantees that if they switch lenders for you that you will even qualify under the new lenders guidlines. Understand that in this market if you are comfortable with the payment and you like the house, buy it. There are too many risk factors that the market, (not you, your lender or your realtor )are in control of. If you gamble for a rate that you "think" you should be able to get because your friend is bragging about how low of a rate he got, be prepaired to lose. Listen to the people that you hired to do a good job for you, your lender and your realtor. They are working to make sure you are happy enough to referr them more business. If you don't trust them, you are working with the wrong team.