A bipartisan group of more than 160 members of the House of Representatives has urged six financial regulators to relax the proposed 5% risk-retention rule for issuers of mortgage securities. In a letter to the agencies, which include Federal Reserve, Federal Deposit Insurance Corp. and the Department of Housing and Urban Development, the lawmakers called the proposals an “overly burdensome government dictate” that could “threaten a full-fledged economic recovery for years to come.”