The announcement that Haider al-Abadi will succeed Nouri al-Maliki as Iraq’s new prime minister is welcome news for Iraqis. Maliki once claimed to seek inclusiveness as Prime Minister. By 2010, however, as political alliances became more clearly drawn along strict sectarian lines and after his delayed appointment to a second term, Maliki turned to sectarian rule with a vengeance. Thus did the potential George Washington of Iraq transform into its Robert Mugabe.

In his first term, Maliki showed signs of potential greatness. For example, he challenged the Shiite militias in Basra and Sadr City in Baghdad in 2008 and then, with considerable U.S. military support, managed to end the fighting in these two Shiite hotbeds. Additionally, he was able to stop the Shiite militia-inspired violence, carried out mostly by the Mahdi Army, in these areas, and set the stage for the Sadrists’ peaceful participation in subsequent elections.

In the lead up to the 2010 election, Maliki claimed to seek inclusiveness in his State of Law Alliance (SLA). However, as the political alliances became more clearly drawn along sectarian lines and between different cliques, Maliki acted forcefully against his perceived Sunni enemies.

Maliki was dubious of a democratic system in Iraq; he doubted it would yield him another term as prime minister. Ultimately he bullied his way through it by challenging the 2010 election results and then appealing to and intimidating the Federal Supreme Court into endorsing the SLA as the winner, even though it had won two less seats than former Iraqi prime minister Ayad Allawi’s Iraqiyah. In the end, after the drawn out process of forming a government, Maliki barely secured the prime ministership.

But at that time the country – including most of the major Shiite political coalitions as well as all the Kurdish parties – was determined to prevent anyone associated with the previous regime, namely the Sunnis, from returning to power. In 2010, it was simply too soon for most Iraqis to countenance the possibility of a Sunni-majority coalition leading the government. So, buoyed by both Shiite and Kurdish support, Maliki’s re-election, however slim, was virtually assured in 2010 despite Iraqiyah’s narrow victory over the SLA.

After his delayed appointment to a second term in 2010, Maliki turned full throttle to sectarian rule. He stepped up the country’s de-Baathification process, even though virtually every senior Baathist had long been purged from national politics. In addition, he amassed wealth, placed loyal Shiite minions into positions for which they were unqualified, including the armed forces, and alienated other Shiite parties and organizations.

After spending more than twenty years in Syria and Iran to avoid being persecuted by former Iraqi president Saddam Hussein, Maliki had developed a deep paranoia of the Sunnis, whom he equated with the Baath Party and Saddam loyalists. So he naturally saw the delay in his re-appointment as the work of Sunni subterfuge. Once formally inaugurated and after the last American forces departed the country, he accused two of the country’s most noted and regarded Sunni leaders, former vice president Tariq al-Hashimi and finance minister Rafi al-Issawi of treason and issued warrants for their arrests. Hashimi was later tried and sentenced to death in absentia.

Maliki further antagonized the Sunni minority – which is still quite large and influential – by cutting off payments to those who had fought al-Qaeda during the Tribal Awakening in 2006-2009. By the end of 2013, he was all but writing off Sunni Iraq, even as the Islamic State in Iraq and al-Sham (ISIS) advanced into Anbar province from Syria, eventually taking control of Fallujah and parts of Ramadi. Eventually, Maliki’s exclusive policies lost him the support of the influential Grand Ayatollah Ali al-Sistani, the Kurdish parties, and the United States. In the end, it seems that even the Iranians may have discarded him.

Now that Abadi has been appointed the new prime minister, he should take heed from Maliki’s experiences, confront the sectarianism that has plagued the political system, and fortify Iraq’s democracy. He must reach out to the Sunnis immediately, perhaps by approaching previously marginalized Sunni leaders and by inviting the leaders of major Sunni tribes and parties to Baghdad to plead for their support in resisting ISIS, also known as the Islamic State. For that, he may need U.S. support and the Obama administration would be wise to partner with Sunni Arab governments, including Saudi Arabia, the United Arab Emirates, and Jordan, to ensure that the Sunnis will have a stake in the nation’s future.

The task of regaining Sunni confidence in Baghdad should not be underestimated. The Sunnis suffered mightily during Maliki’s last four years. But that pales in comparison with the depredations visited upon the Shiites during Saddam’s twenty-four years in power, and many Shiites may still be reluctant to embrace the Sunnis. But it is imperative if Iraq is to continue as a unified state and overcome the challenge posed by ISIS. Sunnis and Shiites, as well as Kurds and the country’s many minorities, must unite under one flag and one government. And this may be their last chance to do so.