Source: NYT BAGHDAD — A roadside bomb struck the convoy of the top United Nations representative to Iraq on Tuesday after he had finished a meeting with the country’s senior Shiite cleric to discuss the continuing political deadlock, officials said. Enlarge This Image Alaa Al-Marjani/Associated Press Ad Melkert, center, a United Nations diplomat, escaped a blast that left an Iraqi dead. Related Kifl Journal: Crossroads of Antiquity Can’t Decide on New Path (October 20, 2010) In a Visit to Clerics, the Iranian Supreme Leader Demands Loyalty (October 20, 2010) The diplomat, Ad Melkert, escaped unharmed, but one Iraqi police officer was killed and three others were wounded in the blast, which tore through their vehicle around 4 p.m. as the convoy drove to the airport outside the southern city of Najaf. A United Nations spokeswoman, Randa Jamal, said she did not know whether Mr. Melkert had been the target of th