Baghdad ? Iran is throwing its weight behind Iraqi Prime Minister Nouri al-Maliki’s bid for a second term, political insiders say, an endorsement that could seal his hold on power.

Tehran wields considerable influence over Iraq’s two largest Shiite blocs, which formed an alliance this month after coming in second and third in the March 7 parliamentary election. That alliance has virtually ensured they will form another Shiite-dominated government — even though a Sunni-backed party won the most seats.

The U.S. is concerned about Iranian attempts to influence Iraq’s political process, a State Department spokesman said Friday. He reiterated Washington’s call not to exclude minority Sunnis from government — something many in Iraq fear could inflame sectarian tensions anew.

Shiite coalitions have ruled Iraq since the end of Saddam Hussein’s regime but were pressured by the U.S. into accommodating the Sunnis. Sunni anger over being largely excluded from government fueled sectarian violence that brought Iraq to the brink of civil war several years ago. The U.S. will not have such leverage as its military role fades.

After a seven-year war and nearly 4,400 American military deaths, a government based on the Shiite alliance could give neighboring Iran the upper hand in Iraq just as the U.S. prepares to pull its remaining combat troops out by the end of August.

Although al-Maliki had close ties with former President George W. Bush and is believed to dislike the Iranians, he may become beholden to Tehran if he wants to hold on to power in a second term.

It is widely believed that Iran, a Shiite country, played a role in pushing through the deal linking al-Maliki’s State of Law with the more conservative and religious Iraqi National Alliance (INA), dominated by supporters of powerful cleric Muqtada al-Sadr, who lives in Iran.

The Sadrists dislike al-Maliki intensely because he crushed their Mahdi Army militia in 2008 and jailed thousands of them. They initially rejected him as head of the new government.

Politicians involved in negotiations say Iran is now urging the Sadrists to back al-Maliki and that the Sadrists are softening.

“Iran has been trying to persuade the Sadrists to let al-Maliki be the prime minister,” said one alliance politician knowledgeable about the negotiations. An INA official confirmed this. Both spoke on condition of anonymity because of the sensitivity of the issue.

They said Iran’s primary goal is to prevent former Prime Minister Ayad Allawi, whose Iraqiya coalition won the most seats, from becoming prime minister.