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With a partisan debate raging in the United States over Iraq policy, Secretary of State Condoleezza Rice said Tuesday that international unity is growing, even among nations once opposed to the U.S.-led invasion.

"In just two days, when Iraqis make history by selecting the most democratic leaders in the entire Middle East, they'll do so with the moral and financial and diplomatic backing of an overwhelming majority of the world. This is remarkable when you consider how sharply divided the world was only three years ago," Rice said Tuesday at the Heritage Foundation.

Earlier at the White House, GOP leaders expressed solidarity behind President Bush's Iraq policy following a closed door briefing with the president, Defense Secretary Donald Rumsfeld, U.S. Ambassador Zalmay Khalilzad and General George Casey , the top U.S. commander, who spoke by video hookup from Iraq. They lawmakers urged patience and warned more violence may accompany this week's elections.

"If it doesn't happen during or before the election, it might well happen during the time that the new government is being formed, which, as all of you I think already know, could take a while," said Sen. Mitch McConnell, R-Ky.

Senior administration officials said the GOP briefings aim in part to arm Republicans against Democratic attacks on the president and their demands for an immediate withdrawal. By the end of the week, nearly 24 "reasonable" Democrats will have separate briefings, aides say.

The latest Gallup poll indicates 63 percent of Americans think Iraq has made real progress in the last two and a half years. But 58 percent say the president lacks a clear plan.

The White House has urged Republicans to point out that Democrats are deeply divided over Iraq, lack a clear alternative of their own and back what the White House calls a "cut-and-run" strategy.

"Unfortunately, the other side has come out with shriller and shriller attacks on this policy and has said things, outrageous things — things that Senator (John) Kerry has said and Howard Dean has said about our troops and about our ability to win this mission," said Sen. Rick Santorum, R-Pa.

Various Democrats including Kerry; Democratic Party chairman Dean; House Minority Leader Nancy Pelosi; Rep. John Murtha, D-Pa.; and Sen. Carl Levin, D-Mich., ranking Democrat of the Senate Armed Services Committee, say the president is failing in Iraq and an open-ended strategy lacking a withdrawal timetable is inadequate.

Other Democrats compare Iraq to Vietnam, but other do not. Some want an immediate U.S. pullout while others, like Nebraska's Ben Nelson, do not.

"I don't think I can say by withdrawing American troops the whole thing settles itself. I don't think it does," Nelson said.

2008 Democratic White House hopeful Sen. Joe Biden, D-Del., the ranking Democrat on the Senate Foreign Relations Committee, says success depends on Iraq's constitution and whether it unites or divides the country.

"Failure to get a consensus constitution spells doom for our policy in Iraq. So what is the plan, Mr. President? That is still lacking," Biden said.

Biden, who left Tuesday night with Republican Sens. Lindsey Graham and Saxby Chambliss to monitor elections in Iraq, said he wants the president to insist that international organizations like the United Nations and NATO, and Iraq's neighbors help draft a stabilization strategy. Without a plan to change to course — not stay the course — he predicts disaster.

"If this time next year nothing has changed in terms of our success rate, then we are going to be out of Iraq. The American people will not sustain this, under no circumstances will they," Biden said.

With Iraqis already voting, the administration calls that stance defeatism and says it ignores both its more flexible approach to conditions on the ground and the fact that Democrats who visited Iraq recently say a plan is in action and it is showing progress.

FOX News' Carl Cameron and Molly Hooper contributed to this report.