It may be possible. The important thing to do is to speak with a lender and look at the whole picture. Your credit is an important aspect of buying but they will also need to look at other factors, income,work history, etc. You also want to discuss with a lender exactly what is on your credit to cause your scores to be so low.
Depending on the situation you may be able to get your scores up. Increasing your chances of getting preapproved.
One thing to make sure is SHOP for the mortgage. Make sure you ask for a Good Faith Estimate and Truth In Lending Statement from anybody that quotes you rates. APR on the TIL will allow an "apples to apples" comparison.