On the sprawling, dusty grounds of Lone Star Army Ammunition Plant and Red River Army Depot in Texarkana, Tex., the recreational vehicles and mobile homes are arriving at a rate of 100 a day before being shipped out to the fringes of Hurricane Katrina's disaster zone.

Those trailers, among 300,000 to be purchased with nearly $5 billion of federal money, have become a focal point of criticism of the Bush administration's early rebuilding efforts. Some conservatives blanch at the cost. And many critics fret that mobile homes will hardly protect their residents from the next storm.

But most of all, housing experts -- conservatives and liberals alike -- worry that Federal Emergency Management Agency encampments will quickly become what former House Speaker Newt Gingrich called "ghettos of despair." Rental vouchers in a market with plenty of available housing would be cheaper and faster and provide better accommodations, they say.

"Three hundred thousand manufactured homes? People are screaming about that," fumed Rep. Jeff Flake (R-Ariz.). "I tell you, FEMA is a disaster."

Beleaguered FEMA officials yesterday counseled patience. When Katrina struck, they were criticized for moving too slowly, they said. Now, they are being second-guessed for moving too quickly.

"The governors and their local officials are looking at all these issues. They're working with all the evacuees in these communities to ensure they are incorporated into the community, they're given job assistance and the help they need," said FEMA spokesman James McIntyre. "We have more than 300,000 displaced households, and they have to live somewhere."

Besides, said Brian Sullivan, a spokesman for the Department of Housing and Urban Development, mobile homes are not the entire response. HUD will expand rental assistance, open federally insured foreclosed homes and offer up vacant public housing units to get Katrina's survivors into shelter. "The initial response now is: Get your hands on anything you can," he said.

When Katrina struck, FEMA did what it has always done in the wake of a major hurricane: turned to its standing list of contractors, including several mobile home manufacturers. Within days, the agency began discussions with the Manufactured Housing Institute, and then purchased 20,000 fully furnished mobile homes and began shipping them to staging areas in Texarkana; Purvis, Miss.; Selma, Ala.; and Baton Rouge, La.

State government then began scouring parks, government land and private sites to establish communities of evacuees. Just as quickly, housing experts of all political stripes began to howl in protest.

"If they simply put poor people in mobile homes, they would be re-creating the same troubled neighborhoods that were destroyed," said Susan J. Popkin, a housing expert at the Urban Institute. "And we know how to do this better."

Bruce Katz, a liberal housing policy expert at the Brookings Institution, rushed to draft an opinion article, urging the administration to learn from the experience of the 1994 Northridge, Calif., earthquake. Within a week of the quake, the first of 22,000 low-income displaced families were moving into new apartments with expanded HUD housing vouchers. Within a month, a major landlord-recruitment effort was pushing low-income Angelenos into higher-income neighborhoods.

"It's not rocket science," said Katz, a HUD chief of staff in the Clinton administration. "If you turned on the voucher faucet, you'd have people in apartments in a week."

Edgar O. Olsen, a conservative housing economist at the University of Virginia, said he pestered the Federal Housing Administration and HUD with faxes, imploring them to scrap the mobile home contracts for rental vouchers.

After all, he noted, rental occupancy rates are at historic lows, as are rents. There are more than 1.1 million available units in the South, with an average rent of less than $700 a month. Houston's vacancy rate stands at 15.6 percent. But Olsen said he has received no response.

The problem, he said, may lie with HUD's organizational chart. Like many other agencies, it has been hollowed out: assistant secretary for public and Indian housing, assistant secretary for policy development and research, general deputy assistant secretary for policy, assistant secretary for fair housing, general counsel, chief financial officer and assistant secretary for administration, all vacant.

Now, HUD will be in the spotlight, Katz predicted. In his 2006 budget, the president had proposed stripping the department of virtually all of its community development functions. The White House has tried to eliminate HOPE VI, the primary housing program designed to raze and rebuild failed public housing complexes. And the administration has de-emphasized the Section 8 housing voucher program.

"The administration has spent the past five years trying to ratchet back the Section 8 voucher program," Katz said. "It's going to be fairly hard for them to turn on a dime and say, 'Oh, we were just kidding.' "

But now, they may have to do just that, housing experts and politicians say. "The whole relief effort was such an incredible screw-up that they felt they just had to throw money at the program," Olsen said, referring to buying the army of trailers. "They had to do it fast. Now, the question is whether they can undo it."

Gingrich agreed: "A key test of the administration right now is to refuse to spend one more penny on such a disastrous policy."

Staff writer Krissah Williams contributed to this report.

Hundreds of mobile homes are at a staging area in Baton Rouge, La., from which they will be assigned as temporary housing for hurricane evacuees.