It's impossible to say precisely how long a large U.S. military force will have to stay in Iraq (search) after power has been handed back to the people there, the No. 2 Pentagon official said Tuesday.

"Next year or year and a half will be so critical. That is time it will take to stand up Iraqi security" forces that are fully trained, equipped and organized and to elect a government to take over from the interim group on June 30, Deputy Secretary of Defense Paul Wolfowitz (search) told the Senate Foreign Relations Committee.

Tuesday's hearing was the latest in a series called by leading military-affairs leaders on Capitol Hill in the wake of continuing resistance to efforts led by the United States in the war-scarred country.

Setting the tone for Tuesday's hearing, Sen. Dick Lugar said: "With lives being lost and billions of dollars being spent in Iraq, the American people must be confident that we have carefully thought through an Iraq policy that will optimize our prospects for success." The Indiana Republican is chairman of the committee.

Sen. Joseph Biden, D-Del., said the campaign "is losing the support of the Iraqi people" and that the "window of opportunity" for American support is closing as well.

The ranking Democrat on the committee, Biden said that coalition successes in rebuilding schools, ministries and other reconstruction "have been dwarfed by two towering deficits the administration created" — one in security and U.S. legitimacy in Iraq.

Sen. Chuck Hagel, R-Neb., criticized Wolfowitz and Deputy Secretary of State Richard Armitage (search) for not knowing precisely how U.S.-run prisons will be handled after the transfer of sovereignty (search).

Armitage said officials hope to put them under Iraqi control "as rapidly as possible" but said he didn't know exactly what that meant.

"I would have thought that this government would put some time into this, especially with what we've just been through the last two weeks," Hagel said of the firestorm over photos of abuse released in the media early this month.

When pressed by Sen. Russ Feingold, D-Wis., to say specifically how long substantial numbers of U.S. troops will have to remain there, Wolfowitz said he couldn't predict.

Occupation forces have signed up some 200,000 Iraqis for police, army, civil defense and other security jobs, but training and equipping them has been slow, insurgent violence is on the rise and Iraqis are far from capable of securing the country without the 160,000-member U.S.-led occupation forces.

Feingold quoted reports that the current 135,000 American forces will have to remain through the end of 2005.

"We don't know what it will be," Wolfowitz said. "We've had changes, as you know, month by month. We've had several different plans. Our current level is higher than we had planned."

Later, Defense Secretary Donald H. Rumsfeld was briefing the House Armed Services panel behind closed doors "on all things Iraq," a congressional aide said. And the defense authorization bill for the fiscal year starting in October was being debated on the Senate floor.

Also, Army Maj. Gen. Antonio Taguba (search), who has investigated the prisoner abuse, held a closed-door meeting Tuesday with members of the House Armed Services Committee.

And House members in the afternoon were being offered a viewing of still-classified photos from the scandal, in which Taguba found numerous "sadistic, blatant and wanton criminal abuses" by military forces at the U.S.-run Abu Ghraib prison (search) complex near Baghdad. The viewing was mostly for those who did not see them last week.

Opening his fifth hearing on Iraq in a month, Lugar said that he feared the Bush administration would lose domestic and international support unless a detailed plan is provided to "prove to our allies and to Iraqis that we have a strategy and that we are committed to making it work."

He said efforts need to be sped up as officials approach the June 30 deadline for handing over power from the U.S.-led occupation authority to an as-yet unchosen Iraqi government. There has been increased violence from insurgents in advance of that transition.