Proponents of an expanded program to refinance underwater Fannie Mae and Freddie Mac mortgages may find a sympathetic ear at the White House, which has talked recently of re-focusing on the struggling housing market, but MBS analysts don’t think the proposal would have a huge impact. Sen. Barbara Boxer, D-CA, early this year introduced the Helping Responsible Homeowners Act, which would require the government-sponsored enterprises to go beyond the limits of the existing Home Affordable Refinance Program, which was implemented administratively. Loans refinanced under the Boxer program could not be ...