A key House Democrat said Wednesday he will work to pass legislation mandating that new rules for mortgage-backed securities apply to federally controlled mortgage giants Fannie Mae and Freddie Mac. The move by Rep. Barney Frank (D., Mass.), the top Democrat on the House Financial Services Committee, represents an effort to reverse a decision announced by bank regulators earlier this week. It also is a rare area of agreement with House Republicans on a potential change to the Dodd-Frank financial overhaul that bears his name.