The government’s failure to overhaul mortgage giants Fannie Mae and Freddie Mac is pushing the U.S. toward nationalization of the mortgage market, and would-be homeowners will be the losers if competition between private companies isn’t restored.

That’s according to Jim Millstein, the former Treasury Department official who oversaw the reorganization of American International Group Inc., who thinks the government will have to get into the business of reinsuring mortgages if it wants to restore the private sector’s role in mortgage securitization, and reduce taxpayer exposure to Fannie and Freddie.

Millstein, the Treasury Department’s chief restructuring officer from 2009 to 2011, says neither the Obama administration nor Congress has put forward a workable plan to lift mortgage giants Fannie Mae and Freddie Mac out of conservatorship.

Increasing the fees charged by the companies and taking all of their earnings threatens to make Fannie and Freddie “permanent wards of the state,” Millstein argues in an editorial he co-wrote with Phillip Swagel, a professor at the University of Maryland School of Public Policy.

Millstein and Swagel have proposed legislation that would create a new government reinsurance program, and turn Fannie and Freddie into one of many private “first loss” insurers that would pay into it.

Four years after the takeover of Fannie and Freddie, they say, “the government now backstops 90 percent of all new mortgages and has no plan to reduce its market share, no plan to protect taxpayers against future losses on the trillions of dollars of mortgage credit underwritten since the firms were placed under government control.”

The Treasury Department’s decision to claim Fannie and Freddie’s earnings as dividends is intended to make sure that taxpayers recoup the $141 billion they’re still owed from bailing the companies out (Treasury has invested $187 billion in the companies and received in $46 billion in dividends). But the government’s “cash sweep” prevents Fannie and Freddie from building up capital reserves that would protect taxpayers against potential losses on $4.5 trillion in mortgage guarantees, Millstein and Swagel argue.

In a similar fashion, recent increases in Fannie and Freddie’s guarantee fees mandated by the Federal Housing Finance Agency would seem “sensible and long-overdue,” the two maintain. Fannie and Freddie, they say, “had grossly underpriced the insurance they provided on mortgages before the crisis, putting taxpayers at risk for the bailout that inevitably came and making it difficult for other private companies to compete with them.”

But the fees are still “significantly below” what private companies would charge, and the increases are all going to the government, rather than helping Fannie and Freddie build up capital and reserves.

“With Washington hungry for revenue, there will be inexorable pressure to milk Fannie and Freddie’s guarantee fees to support other government spending,” Millstein and Swagel warn. “The losers will be potential homeowners, as mortgage availability will be determined by government regulators rather than by private firms competing for their business.”

Ironically, they say, the quickest way to get Fannie and Freddie out of conservatorship and restore competition among private firms is for the government to get into the mortgage reinsurance business. Millstein and Swagel envision a system in which private mortgage insurers would take on a growing proportion of the first loss on bad mortgages before government reinsurance would kick in.

Fannie and Freddie would themselves be transformed into private, “first loss” insurers, and forced to compete with other private companies willing to pay the government for reinsurance.

With “strict regulation to ensure that community banks can originate and securitize mortgages on an even playing field with the giant banks,” competition would breed new entrants in mortgage finance. Any of them, including Fannie and Freddie, could fail without the threat of a housing market collapse, Millstein and Swagel maintain.

A government reinsurance program will be a tough sell to conservatives, they acknowledge. But the government, having placed Fannie and Freddie in conservatorship, is already “creeping” toward nationalization of the mortgage market.

A government reinsurance program with private insurers ahead of the government is perhaps the only way, they say, to shrink Fannie and Freddie’s portfolios, reduce taxpayer exposure, and jump start a competitive private market.

“Today, we’re doing massive guarantees through the conservatorships of Fannie and Freddie,” Millstein tells the Wall Street Journal’s Nick Timiraos. “But it’s a ham-fisted, convoluted way of delivering the guarantee. Taxpayers aren’t being protected at all. There’s no capital ahead of us.”