BAGHDAD: Iraq’s prime minister dismissed his Cabinet secretary Wednesday as part of an ambitious reform drive he said was under threat from corrupt politicians and Shiite militia leaders who use their armed followers for political ends.

A year in office, Haider al-Abadi has launched the biggest overhaul of the political system since the end of U.S. military occupation, enacting a risky package of measures designed to enhance his own power and strip authority from political chieftains who have run Iraq since the fall of Saddam Hussein.

Lawmakers unanimously voted Tuesday to eliminate a layer of senior government posts, scrap sectarian and party quotas for state positions, reopen corruption investigations and give Abadi power to fire regional and provincial bosses.

The bold moves will strip some of Iraq’s most powerful people of official titles, including Abadi’s predecessor Nouri al-Maliki, whose post of vice president is one of those to be abolished.

An official in his media office described Abadi’s decision Wednesday to sack his Cabinet secretary and his aides as “part of a push to cut unnecessary government jobs.”

Abadi’s reform package has garnered public praise from across party and sectarian lines as well as from Western governments. It is also backed by Iraq’s most influential religious authority, Grand Ayatollah Ali Sistani.

But in a televised speech, Abadi said Wednesday he still expected resistance from beneficiaries of the old system.

“The corrupt will not sit idly by,” Abadi said. “Those with interests and privileges will defend their interests and privileges. Some of them will even fight for them. They will attempt to sabotage every step we take toward it.”

While he did not name those he accused of plotting sabotage, he issued a warning against the politicization of Shiite militias, whose leaders have become far more powerful over the past year as their forces have played the main role in battling ISIS militants that seized northern and western Iraq.

“We should remove the Hashd Shaabi from the political field,” Abadi said, referring to a government body that acts as an umbrella for the militias.

Abadi, who Tuesday evening visited troops in western Anbar province gearing up for an offensive to retake the Sunni heartland, has struggled to consolidate his authority.

He took office last summer following the army’s collapse in ISIS’ takeover of the northern city of Mosul, which left the Baghdad government dependent on the Shiite militias to defend the capital and recapture lost ground.

The governing system set up under the 2003-2011 U.S. military occupation included numerous overlapping senior posts, many set aside to be divvied up on ethnic and sectarian grounds among Iraq’s majority Shiites and minority Sunnis and Kurds.

That was intended to reduce strife by keeping the government inclusive. But Abadi has complained that it encouraged ethno-sectarian party patronage, which led to corruption and incompetence so pervasive that it put Iraq’s future in peril.

Abadi insisted his reforms were not targeted at anyone in particular, although he warned that opponents might try to portray him as hostile to particular communities to stir up resentment. “I fear some will try to direct my words toward one individual or another, against a certain group or organization. I do not have anyone specifically in mind.”

Abadi was selected as prime minister in part because he lacked strong ties to the armed groups that fought a sectarian civil war during the U.S. occupation, and was therefore seen as better able to promote conciliation than his predecessor Maliki.

But that has made it harder to stamp his authority on a country enduring war with ISIS, chronic corruption, Kurdish separatism, personal rivalry among political leaders and a financial crisis caused by collapsing prices for oil exports.

Leaders of the Shiite militias “can easily convert their military legitimacy into a political legitimacy, saying no matter what Abadi does, we are those fighting on the front lines,” said Maria Fantappie, Iraq analyst at the International Crisis Group.

While Abadi’s backing from Sistani makes it difficult for the premier’s rivals within the Shiite majority to oppose his measures publicly, they could still try to spoil the reforms from behind the scenes.