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Retired Army Lt. Gen. Jay Garner has been tapped by the Pentagon to work with U.S. companies and a group of Iraqi Americans to prop up and sustain the government of Iraq after a war, the Pentagon announced Tuesday.

Garner, who would act as a civil administrator in Iraq if Saddam Hussein's government is overthrown by a U.S.-led invasion, would report to Gen. Tommy Franks, leader of the U.S. forces.

Teams under Garner would be led by civilian U.S. workers. The official in charge of reconstruction efforts would come from the U.S. Agency for International Development. The "civil administration coordinator" would be a Pentagon official and the humanitarian assistance chief would be a former ambassador, senior officials said.

Pentagon officials say initially the cost of keeping a government in Iraq running could reach billions. But Secretary of Defense Donald Rumsfeld said that money could be found in short order.

"There's the frozen assets, there's the billions of dollars — I think its $10, $11, $12 billion dollars that the U.N. has — plus their oil revenues. And so it's not as though the country is destitute," Rumsfeld said in a briefing with reporters.

But Eric Schwartz, a senior fellow at the Council on Foreign Relations, told the Senate Foreign Relations Committee on Tuesday that costs would be closer to $20 billion for economic aid, humanitarian assistance and peacekeeping in the first year.

"These estimates of requirements are, in fact, quite modest. Other credible estimates are far higher," he said.

The Bush administration is exploring a number of ways to conduct a war without destroying the infrastructure of the country. The goal is to leave water and sewer plants intact and to keep large sections of the electrical grid in place.

Schools, hospitals and police would continue to operate and the United Nations would keep running the Iraqi oil-for-food program. The United States would pay the salaries of Iraqi government officials and the operating budgets of those ministries during the transition, the officials said.

The administration is poised to award $900 million in contracts to U.S. firms who will quickly rebuild Iraqi roads and bridges. Five companies, including Halliburton Corp, formally run by Vice President Dick Cheney, have been asked to submit bids on how they would reconstruct the country.

And Rumsfeld said they could even task former Iraqi soldiers with the rebuilding, assuming that they choose not to fight, and therefore survive the war.

"They are being communicated with privately at the present time. They ... will be communicated with in a more public way, and they will receive instructions so that they can behave in a way that will be seen and understood as being non-threatening," Rumsfeld said. "They will be not considered combatants and they will be handled in a way that they are no longer part of the problem."

No one is making any predictions about how long the U.S.-backed provisional government might remain in place. But the objective is to hand back the country to the Iraqis as soon as possible.

"Our goal in any transition is to stay long enough as necessary to provide security, make sure the appropriate arrangements are in place, but not one day longer," said State Department spokesman Richard Boucher.

Privately, American officials say an Iraqi interim government could be functioning within months. But some Iraq experts disputed that, saying it would be more like years.

The plans are not without controversy at home. On Capitol Hill, a growing chorus of voices want firm answers from the Bush administration about how much the war and the rebuilding will cost.

"There's an arrogance here, to deny the Congress of the United States an opportunity to ask civil questions of people charged with trying to provide estimates of what the cost of this will be. I think Democrats and Republicans are equally disturbed about this," said Sen. Christopher Dodd, D-Conn.

Dodd and Foreign Relations Committee members also expressed anger that Garner did not show up for the panel as he was supposed to on Tuesday.

Committee chairman Richard Lugar, R-Ind., called Garner's failure to appear "arrogant," adding it was "a missed opportunity for the administration to communicate its views on Iraqi reconstruction."

Fox News' Brian Wilson and The Associated Press contributed to this report.