Updated

During one of the worst months of the yearlong Iraq campaign, senators are finding themselves with more questions and fewer answers.

With the rising death toll and increasing fear that the United States lacks an effective plan for success in Iraq, lawmakers Tuesday start a series of hearings in which some hope to talk about how America got into the situation and how it will get out.

It was unclear Monday night how many administration officials will show up at the hearings.

At hearings Tuesday and Wednesday, the Senate and House armed services committees are to hear about current Iraq operations from Deputy Defense Secretary Paul Wolfowitz (search), Joint Chiefs of Staff Chairman Gen. Richard Myers and State Department Undersecretary Marc Grossman.

As of Monday, the Pentagon had not agreed to attend another hearing Thursday on how it intends to transfer political power June 30 to an as-yet unnamed Iraqi government. The hearing was to be the last of a three-day series before the Senate Foreign Relations Committee (search). As of Monday, only former officials, an array of think tank witnesses and Grossman had agreed to attend.

Pentagon officials acknowledged Monday that Wolfowitz and Myers would not go to that hearing, but had no immediate comment on why.

Throughout the week's hearings, officials are likely to face questions on what is being done to calm the increased violence in Iraq, whether troop levels are high enough and exactly how the administration intends to work with the United Nations (search).

U.S. occupation authorities, who long shunned a substantive U.N. role in Iraq, are now counting on it to help devise a plan for forming a new Iraqi government to accept sovereignty on the turnover date.

Democrats probably will focus on mistakes they say got American forces to this point. Their criticisms include: too few troops sent over in the first place; a lack of planning for postwar operations; unilateral action that has left the United States bearing the bulk of the financial and human toll; and overly optimistic predictions on what it would take to oust Saddam Hussein and build a new democratic government in his place.

"Time is rapidly running out on getting it right in Iraq," Sen. Joseph Biden of Delaware, top Democrat on the Senate Foreign Relations Committee, said recently.

Sen. John Warner, R-Va., chairman of the Senate Armed Services Committee, said he remains "steadfastly optimistic," adding, "We'll see our way through this."

But worry about events in Iraq crosses party lines.

The hearings come during the deadliest month in Iraq for U.S. forces since the invasion began — 100 killed in the increasingly violent insurgency. Some estimate over 1,000 Iraqis have died, including civilians, insurgents and police.

Many lawmakers who visited their districts on the just-ended spring recess faced constituents' questions about Iraq.

Polls are showing an increase in the number of Americans who think troops should come home and a reduction in support for the president's handling of Iraq. Already, almost six in 10 of those surveyed say he does not have a clear plan for success in Iraq.

Republicans say Bush eased some Americans' concerns with his news conference last week when he pledged to stay the course in Iraq. Democrats say he was short on details.