Vice President Biden stressed the importance of national unity in calls to top leaders of all three of Iraq's warring divisions on Wednesday.
While traveling in Colombia, Biden called Iraqi Prime Minister Nouri al-Maliki, a Shiite, as well as Suuni leader Osama al-Nujaifi and Kurdish leader Masoud Barzani.
"In each call, the Vice President also stressed the need for national unity in responding to the ISIL threat against all Iraqi communities, for coordination on security issues going forward, and for moving forward with urgency in forming a new government under the constitution."
Sunni extremists affiliated with al Qaeda have rampaged through the country's northern and western regions, clashing with Kurds in the east and the forces representing the central Shiite-controlled government outside of Baghdad.
On Wednesday, militants and government forces battled for control of a pivotal oil refinery that produces more than a quarter of Iraq's energy.
The wave of extremists, known as the Islamic State of Iraq and Syria, has gained a foothold largely because of Sunni frustration with the Maliki government, which has purged moderate leaders from elected office and the armed services.
The White House has said any military action taken by the U.S. to combat the extremists would be predicated on an Iraqi plan for more inclusive government.
In his conversation with Maliki, Biden "discussed the steps required to roll back the terrorists’ advances and made clear the central importance of embedding security measures within a broader strategy to enlist local communities in the fight against ISIL," the White House said.
Biden also "emphasized the need for the Prime Minister—and all Iraqi leaders—to govern in an inclusive manner, promote stability and unity among Iraq's population, and address the legitimate needs of Iraq's diverse communities."
The vice president applauded a joint statement from the leaders declaring the terror network an enemy of all parts of the state, and emphasized they should continue to call on volunteer militiamen looking to protect their communities to "do so through existing laws and security institutions."