Iraqi leaders walked out three hours into the first session of their new parliament Thursday, less than a day after a power-sharing agreement had been reached between Iraq’s four major political parties. Prime Minister Nuri al-Maliki had been allowed to return to office, but members of his main rival bloc, the Sunni group known as Iraqiya, walked out after a dispute over the government’s leadership. Iraqiya won a majority of seats in the elections eight months ago, and voted Thursday to reelect President Jalal al-Talibani as president. A top member of Iraqiya, Jaber al-Jaberi, said there is “still no guarantee from the other side that what they promised will be implemented.” Several members of Iraqiya later returned to the session, suggesting that there is hope for a compromise. Sunnis throughout Iraq say they believe Maliki stole the election, with help from Iran, and many support Iraqiya’s leader, Ayad Allawi, to take Maliki’s place as prime minister.