You have two options, you can stop looking for a house and concentrate on saving money for that down payment, or you can find a lender who will write a mortgage with a high interest rate. The better choice is to concentrate on saving that down payment.
One clever way to do that is pretend that you got the house. Go to one of the mortgage calculators we suggested earlier in this book and plug in the numbers of the house you want without a downpayment. Calculate how much your monthly mortgage payment would be. Now every month pay your rent out of that amount and put the extra into a savings account for that future down payment.