Higher interest rates and concern about the Washington D.C. stalemate over raising the nation's debt ceiling contributed to a drop in U.S. home builders' confidence in October, according to a monthly survey of the nation's home builders. The National Association of Home Builders/Wells Fargo Housing Market Index released today dropped to 53 from 55 in September. Overall, builders' outlooks remain optimistic, but are tempered by the cost and availability of labor and lots, according to a news release.