Investors will have an extra month to bid on Fannie Mae REO properties as part of a pilot program to rent out these homes, according to sources familiar with the process.

The pilot announced in February would sell 2,490 previously foreclosed homes held by Fannie Mae in Atlanta, Chicago, Las Vegas, Los Angeles, Phoenix and parts of Florida. According to several large bidders, who asked to remain anonymous, the Federal Housing Finance Agency originally set a target date in mid April to receive bids, but have now pushed the deadline back to May.

A spokesperson for the FHFA could not confirm the dates but said the program was making progress.

"We are currently qualifying bidders. Qualified bidders will be notified as to the next stage of the process in due course during the evaluation of bidder qualification applications and up and through the bid date. Though we cannot speculate on your timeframes, the transaction continues to proceed as planned," the spokesperson said.

One private investor hinted that the FHFA may be overwhelmed with demand, and said some estimates showed between 300 and 400 bidders were applying, which could have slowed down the process.

The idea of the pilot is to cut down on vacant homes and REO that drag down home prices and spread blight.

The Treasury Department and the FHFA have been working on a plan to sell some of the properties in bulk to investors who would rent the properties.

Over the last year, Fannie, Freddie and the Department of Housing and Urban Development reduced the government inventory of foreclosed homes by 28%. But the three agencies still hold roughly 212,000 properties, according to their financial filings.

Analysis from CoreLogic (CLGX) showed returns for such a REO-to-rental program could total $100 billion.

Some are more skeptical. One asset manager at a large private equity firm based in California said attempting to manage several rented properties spread out over an entire city would cut any yield too thin.

Still, the demand is there judging by the amount of bidders. One analyst at a policy think tank in Washington, who asked not to be named because of the sensitive nature of the developments, said the Treasury and the FHFA face a lot of hurdles for such an unprecedented and important program.

"Administration officials have extremely high hopes for this program," the analyst said. "They say this could be the most important program they've gotten off the ground since the foreclosure crisis struck."