Three key U.S. lawmakers arrive in Amman Friday at the start of a five-day Middle East trip that will also take them to Baghdad, where they will assess U.S. reconstruction efforts in Iraq.

The delegation includes three senior senators on the Foreign Relations Committee: Chairman Richard Lugar, an Indiana Republican, the ranking Democrat, Senator Joe Biden of Delaware, and Senator Chuck Hagel, a Nebraska Republican.

All three have voiced concern about the pace of U.S. reconstruction efforts in Iraq. Senator Lugar addressed the issue at a hearing last month.

"I am concerned that the administration's initial stabilization and reconstruction efforts have been inadequate," he said. "The planning for peace is much less developed than the planning for war."

More than 50 U.S. soldiers have died in Iraq since President Bush declared an end to major combat operations May first as concerns mount over armed resistance to coalition forces.

Senator Biden says the security situation will top his agenda during the trip.

"We would like to, speaking for myself, get a sense of whether or not we have a sufficient number of troops there, is there a need for more police forces or a sort of European-gendarmerie? What kind of gaming and planning has gone on for training Iraqi police?," he asked.

The senators are to meet with Paul Bremer, the U.S. civil administrator in Iraq, as well as U.S. military officials and troops. They also plan to meet with Iraqi representatives.

Before their arrival in Baghdad on Monday, the senators will take part in an international economic forum in Amman to discuss Iraq. They return to Washington Tuesday.

The senators are the first U.S. lawmakers to visit post-war Iraq. The chairman of the Senate Armed Services Committee, Senator John Warner, a Virginia Republican, and the panel's ranking Democrat, Senator Carl Levin of Michigan, are expected to visit Iraq in early July.