Turnout will be the key to success for Iraq's first parliamentary election this week, but significant U.S. troop withdrawals may not be possible until after consensus is reached on a constitution months later, senators said Sunday.

"These are people who are actually running for office that will write laws for the Iraqi people," said Sen. Lindsey Graham, R-S.C. "It will be a chance for the Iraqi people to chart their own destiny. That is a huge sea change."

But given ongoing violence in the country, "I don't think we are going to have any major troop withdrawals any time soon if we are really serious about protecting this infant democracy," Lindsey told NBC's "Meet the Press."

Selected voting begins Monday, with the main balloting on Thursday. The election will be the first under the new constitution ratified in an Oct. 15 referendum and will complete the steps toward democratization following the ouster of Saddam Hussein's government.

Last week, Defense Secretary Donald H. Rumsfeld said he expected 20,000 U.S. troops to return home from Iraq after the elections, and he suggested that some of the remaining 137,000 forces could pull out next year.

The U.S. ambassador to Iraq said he believed the elections could be start of a significant reduction of U.S. troops. "Our hope and expectation is that violence and use of the military means will become less important," Zalmay Khalilzad told ABC's "This Week."

But Sen. Joseph Biden, D-Del., said there could be difficulties if Iraqis fail to reach consensus on a constitution when they vote on it in about four months to six months.

"If it ends up being viewed as a document of division, where the Sunnis think they're out of the deal, then I think we're in real trouble," Biden said on ABC's "This Week."

In an op-ed in Sunday's Washington Post, Secretary of State Condoleezza Rice said U.S. military involvement in the Middle East is necessary to promote global freedom and U.S. security

"Supporting the growth of democratic institutions in all nations is not some moralistic flight of fancy; it is the only realistic response to our present challenges," Rice wrote.

Separately, a Los Angeles Times report Sunday said that more than a year before President Bush declared that Iraq had tried to buy nuclear weapons material in Africa, the French spy service began repeatedly warning the CIA that there was no evidence to support the allegation.

The newspaper described what it said were previously undisclosed exchanges between the U.S. and France in 2001 and 2002. It quoted a retired top French counterintelligence official and a former CIA official.

The CIA declined comment Sunday.