Pressure mounted Saturday on Prime Minister Ibrahim al-Jaafari to step aside as the Shiite bloc's nominee for a second term, with some fellow Shiites urging him to withdraw to break the deadlock over a new government. Elsewhere, a US military helicopter crashed Saturday during a "combat air patrol" southwest of Baghdad but the status of the crew was unknown, the US command said. No other details were released. At least 22 people were killed Saturday in fresh violence in Baghdad and Basra, Iraq's two largest cities. Six others - all Shiites - died Friday evening when gunmen opened fire on a minibus northeast of Baghdad, police said.