The campaign to shoot down a proposal by federal regulators that lenders be required to retain at least 5 percent of the risk on mortgages they securitize when borrowers make down payments of less than 20 percent continues to pick up steam.A coalition of consumer organizations, civil rights groups, lenders, real estate professionals and insurers coordinated with lawmakers today in bringing pressure to bear on regulators, releasing a white paper and joint letters from members of the House and Senate who have taken issue with the proposal.Six federal agencies -- the Federal Reserve, Federal Deposit Insurance Corp., Office of the Comptroller of the Currency, Department of Housing and Urban Development, Securities and Exchange Commission, Federal Housing Finance Agency -- are in the process of...