Baghdad ? The Iranian-backed Shiite parties that helped propel Iraq’s prime minister into power three years ago dumped him Monday as their candidate for re-election, forming a new alliance to contest the January vote.

The move dealt a blow to Nouri al-Maliki’s chances to keep his job next year and set the stage for a showdown between competing factions in the Shiite coalition that had dominated Iraq’s government since the fall of Saddam Hussein in 2003.

Al-Maliki now faces pressure to make a deal with minority Sunni parties to strengthen his position. Because his Dawa party is relatively small, he has never been able to rely on a loyal political base. Instead, he has developed a reputation as a strong leader by crushing militias loyal to anti-American Shiite cleric Muqtada al-Sadr in Baghdad and in the southern city of Basra.