One week after the last U.S. troops left Iraq, a flare-up in sectarian tensions is threatening to not only invite new violence but tear apart the country's fragile political arrangement.
Some officials fear the situation, if not properly handled, could reverse post-surge gains and plunge the country back into a climate of sectarian war. U.S. diplomats have conducted a flurry of phone calls and meetings over the past week in a bid to contain the problem and convince Iraq's political leaders to come together.
At the heart of the dispute is a decision by the government of Prime Minister Nouri al-Maliki, a Shiite, to issue an arrest warrant for Sunni Vice President Tariq al-Hashemi. The vice president is accused of running hit squads against government officials years ago, but Hashemi denies it and has been holding out in Iraq's Kurdish region while Maliki demands he be brought into custody.
Stoking the tensions, a wave of bombings ripped through mostly Shiite neighborhoods in Baghdad Thursday, killing at least 69 and wounding nearly 200. The country's top Shiite cleric afterward blamed the politicians for creating an atmosphere for such attacks.
Amid the chaos, Hashemi has been lambasting Maliki from afar, using a string of media interviews to accuse him of pushing the country toward catastrophe. In an interview with Foreign Policy magazine, Hashemi warned the situation could spiral "beyond control," and likened Maliki to Saddam Hussein.
Maliki in turn has suggested he might abandon a critical power-sharing agreement in Baghdad.
Walid Phares, a Middle East analyst and Fox News contributor, said Saturday that the tensions are a reflection of conflicts that had been "frozen" -- but not resolved -- during the U.S. troop presence.
"As soon as we are out, and there is no political consensus, everything is coming back," Phares said.
While praising the U.S. for its military gains in the country, he said the broader political problems remain -- the conflict between Sunnis and Shiites, and also the presence of Iranian influence which he said is provoking the minority Sunni population.
"It's a spiraling process," Phares said.
"This is a clear sign that the fragile political accommodation made possible by the surge of 2007, which ended large-scale sectarian violence in Iraq, is now unraveling," they said.
The senators claimed the Obama administration's decision not to leave a small residual force in Iraq "precipitated" the dispute.
"If Iraq slides back into sectarian violence, the consequences will be catastrophic for the Iraqi people and U.S. interests in the Middle East, and a clear victory for Al Qaeda and Iran," the senators said. "A deterioration of the kind we are now witnessing in Iraq was not unforeseen, and now the U.S. government must do whatever it can to help Iraqis stabilize the situation."
Administration officials say they have been in constant contact with all sides.
State Department spokeswoman Victoria Nuland said Ambassador James Jeffrey had talks with "the leaders of every major group in Iraq" earlier in the week. Vice President Biden also has been deeply involved, talking to Maliki and other leaders.
In a statement, his office said Biden stressed the United States' commitment to Iraq and the need for leaders to "work through their differences."
"Time and again, the Iraqi people have shown their resilience in overcoming efforts to divide them. We continue to urge leaders to come together to face common challenges," he said, noting the vice president's call for the country to abide by the rule of law.
The administration has not said publicly whether that means the Kurds should turn over Hashemi.
State Department spokesman Mark Toner said the bombings underscore, though, "how critical it is that Iraq's leaders act quickly to resolve their differences."
Asked for an update on the impasse Friday, Toner said: "We remain concerned about the political situation, and we would urge dialogue."
The dispute has created an apparent opening for other voices to resurface. On Saturday, notorious anti-American Shiite cleric Muqtada al-Sadr launched what was described as a peace initiative.
Al-Sadr, whose militiamen were blamed for sectarian killings during the worst years of Iraq's violence, put out a 14-point "peace code" proposal. It warns against spilling Iraqi blood and urges respect for all religions, sects and ethnic groups.
Al-Sadr's aide Salah al-Obeidi described the code as an attempt "to preserve the unity of the country and save it from fighting."
The Associated Press contributed to this report.