PORTLAND (AP) – U.S. Rep. Tom Allen said Monday that his trip to the Middle East last week reinforced his opinion that the time has come to set a deadline for withdrawing U.S. troops from Iraq.

The United States can no longer sustain its current level of troops in Iraq, Allen told reporters in his Portland office. Allen returned to the U.S. late Friday after a trip to Iraq, Afghanistan, Pakistan and Kuwait with a bipartisan congressional delegation.

The only way to remove troops from Iraq is for Congress to pass legislation and force the president to change his policy, he said. The president’s decision to increase troops in Iraq has done little to stabilize the war-torn nation, he said.

“We should be debating not whether we’re going to withdraw, but how soon and how we’re going to leave Iraq,” Allen said. “That’s what I think we need to do.”

Allen, a Democrat, is a six-term congressman but is running for the Senate against Republican incumbent Susan Collins in 2008. He has made the Iraq war the primary issue in his campaign.

While in Iraq, the delegation met with Gen. David Petraeus and Ambassador Ryan Crocker, the top U.S. officials in Iraq. Allen also met with more than a dozen soldiers from Maine.

Allen said he thinks setting a deadline on removing troops from Iraq will put political pressure on the Sunni and Shia political leaders to work out their differences. A deadline would also put pressure on neighboring countries of Iran, Jordan, Saudia Arabia, Egypt and Syria to play a constructive role in Iraq.

“It is impossible for us to referee this civil war,” Allen said. “We cannot do it.”

While Allen said Iraq remains chaotic with little progress toward peace, he was encouraged by what he saw in Afghanistan, which he first visited five years ago.

In Afghanistan, there are 6 million children in school, up from 1 million five years, Allen said. The Afghan army is being built up from 40,000 to 70,000 troops, and the transportation infrastructure is being upgraded.

“Afghanistan can be held together as a country,” he said.

AP-ES-08-13-07 1218EDT