After our visit to Iraq this month, it is clear that what was once unthinkable there is now taking place: A stable, safe and free Iraq is emerging. Violence has fallen to the lowest level since the first months of the war. The Sunni Arabs who once formed the core of the insurgency are today among our most steadfast allies in the fight against al-Qaida. A status-of-forces agreement between Iraq and America will take effect next month, providing for the withdrawal of U.S. troops and a commensurate increase in Iraqi self-defense. And Iraqi politics is increasingly taking on the messy but exhilarating quality of a functioning democracy. While uncertainty and risk remain high, and the gains made are not irreversible, the situation in Iraq has improved dramatically since the dark days before the surge.

It's time for the unthinkable to take place in Washington. For the past several years, Iraq has divided and polarized our parties, our policy-makers and our people. The debate over the war has often been disfigured by politics and partisanship, precluding the national consensus so important to American security in a dangerous world. President-elect Barack Obama has the opportunity to end this destructive dynamic and rebuild a bipartisan consensus on American foreign policy, including the way forward in Iraq. In naming talented, principled and pragmatic leaders to his national security cabinet, the president-elect has already demonstrated that he wants to set aside foreign policy politics as usual. Now the very capable leadership team of Defense Secretary Bob Gates, Secretary of State-designate Hillary Clinton and Gen. Jim Jones, the incoming national security adviser, can apply their bipartisan credentials to help the president-elect forge an Iraq policy that will garner the support of Democrats and Republicans alike.

Our shared, central task now is to work together to support a responsible redeployment from Iraq, based on the new and improved realities on the ground.

To achieve this, the president-elect, his national security team and all of us in Congress should seek the counsel of Gen. David Petraeus, the head of U.S. Central Command, and Gen. Ray Odierno, commander of coalition forces in Iraq. Gen. Odierno was the operational architect of the surge in 2007, when he served as deputy to Gen. Petraeus, as well as of the tribal engagement strategy that persuaded Sunnis to abandon the insurgency and join our side. Gen. Odierno — as the current commander on the ground — is the person whose judgment should matter most in determining how fast and how deep a drawdown can be ordered responsibly.

We are optimistic that President-elect Obama will be able to fulfill a major step of his plan for withdrawal next year by redeploying U.S. combat forces from Iraq's cities while maintaining a residual force to train and mentor our Iraqi allies. However, 2009 will be a pivotal year for Iraq, with provincial and then national elections whose secure and legitimate conduct depends on our continued engagement. By allowing a greater number of forces to remain in Iraq in the short term, we will be able to set the conditions for much deeper troop cuts thereafter.

As we reduce the number of combat forces in Iraq, our national interests there will depend to an increasing degree on the skill of our diplomacy. That is why we urge the outgoing Bush administration to act quickly, and in coordination with the incoming Obama administration, to put in place an appropriate successor to Ambassador Ryan Crocker, who has announced his intention to leave his critical post in Baghdad early in the new year.

Ambassador Crocker has done heroic work in forging constant and unprecedented cooperation between the U.S. Embassy and the military — precisely the kind of close civil-military partnership that is at the heart of successful counterinsurgency. To ensure that this collaboration continues, we believe it is imperative to appoint an individual of the greatest possible skill and proven ability — preferably, someone who can be in Iraq before Crocker departs.

By safeguarding our gains and managing the coming transition in Iraq responsibly, we have the opportunity to turn what has in recent years been a strategic liability into a strategic asset.

Iraq can serve as an anchor of stability in the region, a counter to Iranian hegemony and a model of democracy for the Middle East.

That is what makes it all the more important that Republicans and Democrats put aside the differences over Iraq that have divided us. The president-elect has the chance to repair this breach in our politics by adopting a set of policies that all of us — Democrats and Republicans alike — will be able to support.

John McCain, R-Ariz., Joe Lieberman, I-Conn., and Lindsey Graham, R-S.C., are members of the U.S. Senate. They wrote this commentary for The Washington Post.