The Bush administration is falling short in its efforts to rebuild Iraq, increase oil production and spawn a new government that is representative of all factions there, lawmakers of both parties said Tuesday.

Testifying before the Senate Armed Services Committee, Defense Secretary Donald H. Rumsfeld heard from critics including panel Chairman John Warner, R-Va. The comments marked a continuation of bipartisan criticism the administration has received in recent months from members of Congress over its Iraq policies.

Warner said that without an effective Iraqi government that has leaders with "strong backbones, not subject to secular pulls," it was unclear whether U.S. troops would be able to return home even if Iraq's military and security forces are competent.

At the same hearing, after repeated questioning about stress on the National Guard and Reserve, Joint Chiefs of Staff Chairman Gen. Peter Pace told lawmakers that the nonactive duty forces will play a much smaller role over the next year in Iraq and Afghanistan.

Pace said Guard and Reserve troops would make up 19 percent of the U.S. forces there, compared with 30 percent currently. There are 138,000 troops in Iraq and 19,000 in Afghanistan.

Bush administration officials have been saying they hope to reduce the number of U.S. troops in Iraq this year, assuming the Iraqi government and its forces can take a wider role in the war and keeping order.

Pace said only one Iraqi army battalion is capable of fighting without U.S. help. That is the same number as in September, when U.S. commanders disclosed that the number of such highly trained battalions had dropped from three to one, prompting criticism from lawmakers.

The administration has been under pressure to bring more American troops home. A study commissioned by the Pentagon said last month that the wear and tear of the U.S. deployment in Iraq was beginning to wear down the Army and questioned how much longer it could continue operating there at full effectiveness.

Rumsfeld acknowledged difficulties the United States is facing in Iraq and urged patience. Ultimately, he said, "The Iraqi people are going to have to rebuild that country."

"It's our job to do what we've been doing — to help create an environment where they can do that, to launch them on the path for democracy, to train up their forces so that they can provide security while the building process takes place in the years ahead by the Iraqi people," Rumsfeld said.

That response didn't appear to appease lawmakers.

Sen. Carl Levin of Michigan, the panel's top Democrat, said the Bush administration has failed to clearly tell Iraqis they must amend their constitution to ensure power and resources are shared equitably and a government is created that reflects the country, not sectarian groups. The newly elected Iraqi parliament seems likely to be controlled by Shiites, leaving Sunnis with a small role.

"The only hope we have of defeating that insurgency is if they will put their house in order politically," said Levin.

On the economic front, Sen. John McCain, R-Ariz., said "the news is not so good" given that Iraqi oil revenues are lower than before the U.S.-led invasion nearly three years ago.

"If that isn't fixed we're in significant difficulty. And we all recognize that's a matter of security," McCain said.

Sen. Joseph Lieberman, D-Conn., said he was troubled by the administration's suggestion that it wasn't likely to contribute any more U.S. money for Iraq's reconstruction.

"Look, you can cut and run economically as well as you can militarily," Lieberman said.

Warner said that beyond its military, the United States must involve more U.S. agencies in the work of helping Iraq.