BAGHDAD — The last time the United States pushed Iraqis to choose a new prime minister who could unite the country to confront a sectarian civil war was in 2006, and the Iraqis chose Nuri Kamal al-Maliki. The result was another civil war. This time, with the country again on the edge of collapse, they have chosen Haider al-Abadi.

Both men come from the same Shiite Islamist movement whose members, after decades of clandestine opposition to Saddam Hussein and the Sunni elite that dominated his rule, were asked to govern Iraq in an inclusive way that accommodated the Sunnis they considered their former tormentors.

So far, that has proved elusive, but this time hope rests on a belief that Mr. Abadi is a different type of Islamist: one whose education, big-city upbringing and decades of living in Britain can surmount what have seemed the reflexive positions of Iraqi Shiite Islamists to be suspicious of Sunni ambitions and to see conspiracies around every corner.

In some ways, though, he is solidly in line with the traditional sectarian views held by Shiite Islamists in Iraq. Mr. Abadi, who was nominated last week to be Iraq’s new prime minister and still must form a government before he takes power, insisted a few years after Shiites took power during the American occupation that they could not soon be expected to support a reconciliation program with the country’s Sunni minority.