Wednesday's ceremony will signal a shift toward a greater U.S. diplomatic role as the military mission dwindles seven years after the American invasion that toppled Saddam Hussein.
Underscoring the shift, officials said Biden will make a new appeal to Iraqi leaders, including Prime Minister Nouri al-Maliki, to end the political deadlock and seat a new government. March 7 parliamentary elections left Iraq without a clear winner, and insurgents have exploited the uncertainty to hammer Iraqi security forces in near-daily attacks.
Biden and al-Maliki will meet Tuesday morning "to discuss the political situation and withdrawal, and Iraqis taking over responsibility for security," the prime minister's adviser, Yasin Majeed, told The Associated Press.
It was the vice president's sixth trip to Iraq since he was elected and, officially, he came to preside over a military change-of-command ceremony. On Wednesday, Gen. Ray Odierno ends more than five years in Iraq and hands over the reins as commander of U.S. forces here to Lt. Gen. Lloyd Austin. Austin also has served extensively in Iraq, most recently as commander of troop operations in 2008-09.
But the Sept. 1 ceremony also marks the start of the so-called "Operation New Dawn" - symbolizing the beginning of the end of the American military's mission in Iraq since invading in March 2003.
Just under 50,000 U.S. troops remain in Iraq - down from a peak of nearly 170,000 at the height of the 2007 military surge that is credited with turning the tide in Iraq as it teetered on the brink of civil war. Additionally, U.S. troops no longer will be allowed to go on combat missions unless requested and accompanied by Iraqi forces.
Under a security agreement between the two nations, all U.S. forces must leave Iraq by the end of 2011. But the Obama administration, sensitive to charges of American abandonment, has directed its diplomats to step into the void and help Iraq's weak government, economy and other institutions get back on their feet for years to come.
Threats still remain.
Al-Maliki last week put Iraq on its highest level of alert for possible attacks by al-Qaida and Saddam's former Baath Party loyalists in the days leading up to the U.S. ceremony on Wednesday. An Iraqi intelligence official said suicide bombers are believed to have entered Iraq with plans to strike unspecified targets in Baghdad, the capital.
And on the eve of Biden's arrival, Iraqi police said two mortar rounds landed in the capital's Green Zone, where the parliament and many foreign embassies are housed behind blast walls, steel gates and barbed wire. The rounds landed near the U.S. Embassy but did not kill or injure anyone, police said.
All Iraqi security officials spoke on condition of anonymity because they was not authorized to discuss sensitive information with the media.
Al-Maliki, a Shiite, is struggling to keep his job after his political alliance narrowly came in second place to the Sunni-backed Iraqiya coalition in the March 7 vote.
U.S. diplomats have encouraged a power-sharing agreement between Iraqiya and al-Maliki's State of Law alliance. Together, they would control a majority of parliament and win the right to choose the new government's leaders.
But al-Maliki and Iraqiya's leader, former Premier Ayad Allawi, both want to be prime minister. So far, neither has backed down - creating a political impasse and leading to back-room jockeying by hard-line Shiite groups for a larger share of power.