The administration is expected to include three options for a post-Fannie and Freddie world when it releases a long-awaited proposal for the future of the nation’s $10.6 trillion mortgage market, which could come as soon as Friday. Together with federal agencies, Fannie and Freddie have accounted for nine of 10 new loan originations in the past year.

The White House’s “white paper” will begin what promises to be a prolonged and fiery debate about the future of how homes are financed across the U.S. Any wind-down of Fannie and Freddie would happen gradually to avoid roiling markets, and the central, unanswered question is what kind of federal function, if any, the administration and Congress will invent to take their place.

Steps to reduce the government role in the mortgage market likely would raise borrowing costs for home buyers, adding pressure on the still-fragile U.S. housing markets. Consequently, analysts believe any transition could take years and would be driven by the pace of the housing market’s recovery.