He is the most powerful federal employee you’ve never heard of. Edward DeMarco has slowed the economic recovery with the stroke of a pen. His actions are costing taxpayers tens of billions of dollars, forcing millions of homeowners to lose their homes, and contributing to the falling housing prices that are a brake on the recovery.

Not bad for an obscure “acting director” who should have departed his position long ago.

Edward DeMarcoheads the Federal Housing Finance Agency (FHFA). He’s a temp, in office only because — no surprise — Senate Republicans, led by Richard Shelby (Ala.), refused even to allow a vote on the man President Obama nominated for the post.

And DeMarco is philosophically opposed to the common-sense solutions needed to deal with the housing crisis.

When Fannie Mae and Freddie Mac — holders or guarantors of about 60 percent of housing mortgages — were bailed out, the FHFA was tasked with supervising their activities, with a mandate to minimize taxpayer losses. That gives DeMarco extraordinary power.

As the Federal Reserve has detailed, falling housing prices are a continuing drag on the recovery. Homeowners have lost a staggering $7 trillion in the value of their homes since early 2006 as home prices fell an average of about 33 percent. Homes are the prime investment of middle-class families, and when home values fall, families begin to cut back on purchases. This slows the entire economy.

With foreclosure, the effects are even worse. Foreclosure is a tragedy for those who lose their home and an economic calamity for their neighbors, who watch their houses plummet in value. It is costly to creditors, for the loss on foreclosed properties often exceeds what might be gained through renegotiating the mortgage. And foreclosures in large numbers impede a recovery, driving housing prices into a death spiral.

The Federal Reserve concludes that is what we face now. Millions have lost their homes already, and millions more are on the verge. A stunning 12 million homeowners — one in five with mortgages — are “under water,” meaning their homes are worth less than their mortgage.

Some of these victims had taken former Fed chair Alan Greenspan’s advice and took out a subprime or variable-interest loan with a small down payment to buy a house, on the assumption that values would continue to rise. When prices fell, these buyers not only lost their down payment, they couldn’t refinance their loans when their variable rates kicked up.

More of these underwater homeowners, however, are simply bystanders — collateral damage — to the banking folly. They hold prime mortgages, put down 20 percent and now find themselves unable to refinance or to sell. Their investment is gone.

So a growing chorus of voices — from Obama to Fed Chairman Ben Bernanke — have called for programs that would refinance underwater loans, particularly by reducing the principal owed so homeowners can stay in their homes.

Small-scale experiments have shown this approach can save creditors money. But the banks want to avoid putting a real price on the mortgages they own for as long as possible, while loan servicers are set up to manage loans, and often have neither the staffing nor the incentive to deal with homeowners in trouble. One aim of the multibillion-dollar settlement just inked by attorneys general of several states and five big banks was to require the setup of procedures to facilitate refinancing and principal reduction.

Fannie and Freddie hold over 20 percent of underwater mortgages, so Bernanke, President Obama and leading senators and legislators have called on DeMarco to let Fannie and Freddie move on principal reduction. The Treasury Department even offered to provide 63 cents for every dollar of principal reduction to subsidize the process.

According to the FHFA’s own reports, done carefully, this might save taxpayers $28 billion, compared to the cost of foreclosures. But Edward DeMarco says no. He even shut down a test program in principal reduction before it got started.

“He’s acting as if he was head of two private companies called Fannie and Freddie and not taking into account the impact this has on the economy, and I think he should be more cooperative with efforts to reduce foreclosures,” argues Rep. Barney Frank (D-Mass.).

DeMarco argues that he has no authority to allow principal reduction because his mandate is to minimize taxpayers’ losses. But Reps. Elijah Cummings (D-Md.) and John Tierney (D-Mass.), both members of the House Committee on Oversight and Government Reforms, noted that the FHFA’s own figures show a sensible program could save taxpayers billions — to say nothing of the benefits of buoying housing prices, keeping other homeowners above water, and helping the economy get going.

“If DeMarco were fire chief and your house became engulfed in flames, you could forget about calling 911,” argues the Huffington Post’s Peter Goodman. “He would not run up the municipal water bill by saving your block.”

Clearly DeMarco should go. Without Shelby’s obstruction, he’d already have been gone. Now the pressure is building. Liberal groups — MoveOn, the Campaign for America’s Future, Rebuild the Dream and the New Bottom Line, among others — have joined in petitions calling on the president to fire DeMarco and make a recess appointment to replace him. Last week, demonstrators marched outside regional Fannie and Freddie offices, calling on DeMarco to go. The Congressional Progressive Caucus has signed a letter telling DeMarco to act or to leave.

A recess appointment would trigger a partisan brawl with Republican senators that the White House has little appetite for. But to save taxpayers billions, to help families keep their homes and to give a boost to the economy, getting rid of the most destructive man we’ve never heard of is a small price to pay.