BAGHDAD - A prominent Iraqi Sunni cleric who urged Islamist armed groups to end their insurgency was critically wounded, and four of his bodyguards killed, when a car bomb hit his convoy in Baghdad on Sunday. Mehdi al-Sumaidai, who once fought U.S. troops in Iraq and was part of a Sunni body issuing religious edicts, had been negotiating with insurgent groups who vowed to fight on after the withdrawal of American troops in December. The attack came as al-Qaida's local wing, Islamic State of Iraq, has warned of a new campaign and security analysts say fighters in Iraq are benefiting from funds and morale from Islamists slipping into Syria to join the revolt against President Basher Assad next door.