BAGHDAD — The decision by Iraq’s embattled Nouri al-Maliki to step down as prime minister revived hopes today for the formation of a new government that could take on a growing insurgency by Sunni militants that has engulfed much of the country.

The move, which followed weeks of international and domestic pressure, defuses a political deadlock that has plunged Iraq into uncertainty at a time of the nation’s greatest turmoil since the 2011 withdrawal of U.S. troops

Al-Maliki announced he was giving up his post on national television late Thursday, standing beside senior members of his Shiite Islamic Dawa Party, including his rival and premier-designate Haider al-Abadi.

He said he was stepping aside in favor of his “brother,” in order to “facilitate the political process and government formation.”

Al-Abadi, a veteran Shiite lawmaker, now faces the immense challenge of trying to unite Iraqi politicians as he tries to cobble together a Cabinet over the next 30 days. The country’s major political factions deeply distrust each other and the army seems unable to regain territory in the north and west taken by Islamic State militants.

Al-Maliki had been struggling for weeks to stay on for a third four-year term as prime minister amid an attempt by opponents to push him out, accusing him of monopolizing power and pursuing a fiercely pro-Shiite agenda that has alienated the Sunni minority.

The United States, the U.N. and a broad array of political factions in Iraq had backed al-Abadi, saying only a new leader could unify a country under siege from the Islamic State extremists who have captured large swaths of territory.