Republican supporters of legislation that would allow federal mortgage insurance on zero-downpayment loans are asking the Congressional Budget Office to reconsider controversial estimates challenging claims that the measure would raise $200 million in additional revenue. In a July 22 letter, Ohio House Republicans Bob Ney and Pat Tiberi urged CBO Director Holtz Eakin to consider an analysis in which the Department of Housing and Urban Development lowered its revenue estimates to $27.6 million a