Baghdad ? When the coalition led by Iraqi Prime Minister Nouri al-Maliki narrowly lost at the polls, he raised the prospect that he could pull ahead by gaining the support of other Shiite-dominated alliances. Since then the largest of those groups have been reaching out — but not to him.

Al-Maliki’s secular challenger, Ayad Allawi, gained a significant advantage when he won the unexpected support of a major Iranian-linked Shiite party. That came after anti-American Shiite cleric Muqtada al-Sadr made a move widely seen as ominous for al-Maliki: asking his followers to decide which candidate his movement should support in a two-day, unofficial referendum that began Friday.

Those developments may be only the beginning of a flurry of dealmaking that will determine the leader of Iraq’s new government, but they highlight al-Maliki’s struggles to overcome his personal unpopularity among rival Shiite leaders.

The leading contenders in the March 7 election each failed to score a decisive win, which left them scrambling to get enough parliamentary support to form a government. Allawi’s cross-sectarian bloc tapped into heavy Sunni support to come in just two seats ahead of al-Maliki’s mainly Shiite list, 91-89; 163 seats are needed to rule.

Many fear a drawn-out political debate to form a government could spill over into violence and complicate American efforts to speed up troop withdrawals in the coming months.

The close results raise the prospect of unlikely alliances, but the support Allawi received Thursday night from the Iranian-linked Supreme Islamic Iraqi Council was particularly stunning because Allawi has been outspoken against the influence of Tehran and religious parties.

Allawi, himself a Shiite who was prime minister in 2004-2005, also has been seen in the past as a U.S. puppet who drew the ire of both Shiite and Sunni Muslims. His backing of the U.S. offensives to take back the Sunni city of Fallujah in Anbar province in 2004 and against al-Sadr’s Shiite militiamen in Najaf that same year was deeply unpopular at the time, though now supporters say his decisions show that he does not play favorites in cracking down on sectarian conflict.