As U.S. officials pressed Iraqis to finish work on a new constitution, a leading Democratic lawmaker said Sunday the Bush administration is downgrading expectations for a flourishing Middle East democracy — signaling a possible exit strategy.

"They have squandered about every opportunity to get it right," said Sen. Joseph Biden (search) of Delaware. "The bottom line is they are significantly lowering expectations."

Biden, ranking Democrat on the Senate Foreign Relations Committee, also told NBC's "Meet the Press" he has seen no evidence that the Sunni-led insurgency in Iraq (search) is losing steam as a political force -- an assertion made recently by Secretary of State Condoleezza Rice.

Administration officials, according to a Washington Post article Sunday, said they are scaling back some of their expectations for Iraq, such as the transformation of the country into a model new democracy.

Biden and another top U.S. lawmaker, Republican Sen. John McCain (search) of Arizona, said it's premature for the United States to begin plans for withdrawing troops from Iraq.

"The day that I can land at the airport in Baghdad and ride in an unarmed car down the highway to the Green Zone is the day that I'll start considering withdrawals from Iraq," said McCain, referring to the heavily fortified area where U.S. and Iraqi government headquarters are located.

"We not only don't need to withdraw, we need more troops there," he said on "FOX News Sunday."

The U.S. ambassador to Iraq, Zalmay Khalilzad (search), said it was possible that the United States would put more troops on the ground in Iraq ahead of another round of elections in December.

Khalilzad predicted that Iraqis would complete a constitution by Monday's deadline.

"The Iraqis tell me that they can finish it and they will finish it tomorrow," he said during one of several appearances on the Sunday talk shows. "There are options, obviously, should they need it, but at this point, my information is -- and I've just come from a meeting with the Iraqi leaders --that they intend to finish it tomorrow."

McCain said all Iraqis have a vested interest in the outcome of the draft negotiations.

"I think it's very important that it not be a perfect constitution but it certainly be one that protects the rights of all minorities and all ethnic groups in Iraq," he said.

To battle the insurgents, Khalilzad said Baghdad needs to do more to encourage neighboring Iran and Syria to prevent foreign terrorists from crossing into Iraq.

"The neighbors can make it harder. It can take longer. But success is inevitable," Khalilzad said. "This country has the resources to become a very rich and powerful country. It behooves the neighbors of Iraq to help."

Since the war started in March 2003, more than 1,840 members of the U.S. military have died. The United States has 138,000 troops in Iraq, and military officials had recently discussed "fairly substantial reductions" in forces early next year, if the situation on the ground stabilized.

But Bush last week dismissed talk of troop cuts or increases as "speculation and rumors."

Democratic National Committee Chairman Howard Dean said the administration needs a plan.

"Some of the generals have said we can withdraw some of the troops. ... We have others saying, we're not going to leave. These people do not know what they are doing," Dean said on CBS' "Face the Nation.