Top US officials Wednesday upped pressure on key Iraqi leaders as political chaos in Baghdad clouded American hopes for a unity government to tackle the country's sectarian breakdown. President Barack Obama, meanwhile widened the US effort to convince key regional powers to prevail on Iraqi factions for a political settlement, calling Saudi Arabia's King Abdullah. Vice President Joe Biden, who frequently burns up the phone lines to Baghdad, talked to the speaker of Iraq's previous parliament, Osama al-Nujaifi, a prominent Sunni leader.