As the United States transferred political control to an interim government in Baghdad, U.S. lawmakers are expressing unease about the future of Iraq (search) and the 138,000 American troops who will continue to serve there.

Over the past week, Democrats have pointed to rising violence, an uncertain political process and continued delays in restoring electricity and other basic services. They question when Iraqis will be able to defend themselves, how long U.S. troops will have to remain in the country and whether they have adequate financial support.

While Republicans are more optimistic, some are concerned that U.S. troops could be endangered if the new Iraqi government has too much of a say in military matters. U.S. officials will remain in charge of Iraqi security but have promised to work closely with the new government.

In a surprise move Monday, apparently aimed at catching off guard insurgents who may have tried to sabotage the step toward self-rule, the American-led coalition handed over sovereignty to an interim Iraqi government.

The initiative came as President Bush met with world leaders for a NATO summit in Turkey. The administration applauded the move in Baghdad and said it was a proud day for Iraq.

Last week, House Armed Services Committee Chairman Duncan Hunter, R-Calif., told Pentagon (search) officials it is important "that we don't have American military commanders who feel that they're compelled to do certain things because there are Iraqi requests to do it."

Congress gave Bush broad bipartisan support for going to war with Iraq and united behind him as the U.S.-led coalition sped through the country and toppled Saddam Hussein's government.

But criticism grew soon after Bush declared an end to major combat on May 1, 2003, as U.S. casualties continued to rise and inspectors failed to find stockpiles of weapons of mass destruction (search) that were the chief argument for the war. Republicans joined Democrats in denouncing sloppy intelligence, poor planning for the postwar occupation and inadequate troop levels.

Complaints have diminished somewhat in recent weeks following the appointment of Iyad Allawi (search), a former Iraqi exile with close U.S. ties, as interim prime minister and administration efforts to seek more international support for its efforts in Iraq.

On Monday, the NATO alliance agreed to an Iraqi request to help train its armed forces.

"Although late in coming there is finally a real diplomatic" effort on the part of the administration to get international help, Sen. Carl Levin, ranking Democrat on the Senate Armed Services said Friday at a hearing on the transition.

But with Iraq a central issue in the presidential election, Democrats have been pressing their attacks and Republicans are rushing to Bush's defense.

The top Democrat on the House Armed Services Committee, Rep. Ike Skelton of Missouri, told Deputy Defense Secretary Paul Wolfowitz (search) that the successes depicted by Pentagon officials contrast with the daily images of "the violence, the deaths of soldiers and Marines."

Democrats have also been skeptical that the $25 billion Bush requested for military operations in Iraq and Afghanistan will be sufficient. The nonpartisan Congressional Budget Office (search) estimated Friday that the cost will probably be $55 billion to $60 billion if troop levels remain unchanged.

"No doubt, after the election the public will be told what the facts are on the installment plan" about Iraq spending, the top Democrat on the House Appropriations Committee, Rep. David Obey of Wisconsin, said Tuesday.

At Friday's hearing, Sen. Edward M. Kennedy, D-Mass., questioned how Americans would know when the Iraq mission was a success. "How do we know we're not just ending up with an unending commitment with no way out?" he asked.

Wolfowitz said "there's a clear path to success," which he defined partly as when the enemy is defeated or decides "to come in and join the new Iraq."

Sen. Joseph Biden of Delaware, top Democrat on the Senate Foreign Relations Committee, said on a network news show on Sunday that he did detect some overall progress in Iraq. "It's going to get worse initially, but I think it will get better," he said.

Republicans stress the importance of ending Saddam's brutal regime and setting the stage for an elected government. They accuse Democrats of seeking a rapid and potentially disastrous withdrawal of U.S. forces.

"It seems like the pressure is on to get out quickly and dirty, and it doesn't really matter what the consequences of getting out quick and dirty are," said Rep. Rob Simmons, R-Conn.

At the Senate hearing, Armed Services Chairman John Warner, R-Va., praised Bush's handling of Iraq as brave and consistent: "He is determined we will succeed. We will, and we must."