A controversial plan to create a Ginnie Mae securitization option for low-downpayment conventional mortgages could have a meaningful, positive impact on a federal budget that is staring once again at deficits, according to a new study released this week by proponents of the plan. The so-called Ginnie Mae Choice program could bring some $219 million in lifetime earnings to the Department of Housing and Urban Development, according to a study by Ann Schnare, of the