Mortgage rates declined for the second week in a row, with the benchmark conforming 30-year fixed mortgage rate now 4.68 percent, according to Bankrate.com's weekly national survey. The average 30-year fixed mortgage has an average of 0.39 discount and origination points.

The average 15-year fixed mortgage held steady at 3.82 percent while the larger jumbo 30-year fixed rate retreated to 5.17 percent. Adjustable rate mortgages moved lower also, with the average 5-year ARM sliding to 3.36 percent and the 7-year ARM falling to 3.64 percent.

Mortgage rates continue to hover near the low point of 2011, aided by a persistently weak economy. Nervousness in financial markets overEurope's debt issues has also contributed to low mortgage rates. But the ongoing debt ceiling debate here in the U.S. and the prospect of a U.S. credit rating downgrade warrant attention from prospective mortgage borrowers. In the event of either a U.S. debt default or just a downgrade, mortgage rates would rise sharply in response.

The last time mortgage rates were above 6 percent wasNov. 2008. At the time, the average 30-year fixed rate was 6.33 percent, meaning a$200,000loan would have carried a monthly payment of$1,241.86. With the average rate now 4.68 percent, the monthly payment for the same size loan would be$1,034.87, a difference of$207per month for anyone refinancing now.