Iraqi security forces, supported by coalition airstrikes, are clearing territory northwest of Baghdad along the Euphrates River valley as they continue to prepare a push to retake the Islamic State group-held city of Mosul. But progress on the ground has been slowed by skirmishes elsewhere and by a political crisis that has prompted the government to pull some forces back from the front to secure the capital.

Amid these distractions, Iraqi forces are concentrating on the IS-held town of Hit in the western province of Anbar. Commanders here say the battle for Hit is key to building on their current momentum, cutting Islamic State supply lines and linking up government forces to the west and the north of Baghdad in preparation for an eventual push on Mosul.

"Hit is the support line from Syria for Daesh," said Gen. Ali Aboud with Iraq's elite counterterrorism forces, using an Arabic acronym for the Islamic State group. "All of Daesh's logistical support in Anbar comes from that place."

Aboud spoke to The Associated Press from a makeshift base in the town of Tash, west of the provincial capital Ramadi, which now serves as the Anbar operations command center. Behind him a team of two men from his unit spoke to Australian coalition troops on a radio, confirming coordinates and calling in airstrikes: one on Hit, another on the outskirts of Ramadi.

But despite close coalition support and Iraq's respected and battle-tested counterterrorism troops taking the lead, the operation to retake Hit from IS, launched weeks ago, has been stalled by political unrest in Baghdad.

Influential Shiite cleric Moqtada al-Sadr mobilized thousands and staged a sit-in outside Baghdad's highly fortified Green Zone on Friday. The cleric called for political reforms in February amid growing concern regarding Iraq's economic crisis — triggered in part by the plunge in global oil prices. Sadr's show of force on the streets was meant to put pressure on Iraq's political leadership. His supporters pushed past razor wire and checkpoints to reach the walls of the Green Zone, home to Iraq's political elite and most of the country's foreign embassies.

"We had to move four battalions back to Baghdad," said an Iraqi counterterrorism commander at the Tash base. Iraq's counterterrorism forces fall under the direct control of Prime Minister Haidar al-Abadi and some were ordered back to Baghdad late Friday night after al-Sadr's supporters defied a protest ban.

"Honestly we were supposed to already be in Hit by now," said the commander, who spoke on condition of anonymity as he was not authorized to brief the press. "Once this problem of protests is solved," he said, "we'll be able to make progress again in Hit."

Political dysfunction in Baghdad has stalled military operations in the past as the country's disparate — and sometimes clashing — anti-IS forces have at times proven unable to work together cohesively.

The plan to retake Mosul, the country's second largest city that has been under IS control for nearly two years, has also faced complications stemming from the Iraqi forces' recent successes on the ground. As the troops advance against IS, the government's front lines and supply lines have been extended — increasingly leaving troops exposed to anti-IS counter attacks.

Aboud of the counterterrorism forces said suicide car bombs continue to be particularly deadly even as government forces advance northwest across Anbar province.

Early Monday morning four cars laden with explosives hit an Iraqi military checkpoint along the Euphrates River valley just 27 miles (45 kilometers) north of the Hit operation. Iraqi military officials say the attack killed at least five Iraqi troops. Such attacks are increasingly common as Iraqi government forces snake through open desserts that are under neither government nor IS control.

"The car bomb is the only effective weapon Daesh has," Aboud said.

Much of Iraq's north and west fell to the Islamic State group in the summer of 2014, but over the past year Iraq's military has slowly clawed back pockets of territory. While IS still controls a large swath of Iraq and neighboring Syria, the group has lost an estimated 40 percent of the territory it once held in Iraq, according to U.S.-led coalition officials. In February, government forces scored a major victory and declared the city of Ramadi, capital of Anbar province, to be "fully liberated."

Over the past 10 days, as coalition airstrikes on Hit have increased and Iraqi forces have closed in on the small Euphrates river town, counterterrorism forces say more than 10,000 civilians have fled. Most have sought shelter in already overcrowded camps between Hit and Ramadi while others have moved further east to towns under Iraqi government control.

Meanwhile battles on the outskirts of Ramadi continue, further slowing the progress of the government forces. While the city itself is in government hands, the outskirts are still being painstakingly cleared of IS fighters. Since the February declaration that the town was liberated, coalition planes have conducted near-daily strikes around Ramadi, according to coalition statements.

At a checkpoint on the western edge of Ramadi, a line of cars and trucks carrying families fleeing Hit wait as Iraqi army officers check papers and search through luggage. Um Ahmed, traveling in the back of a truck carrying more than 30 women and children, said they were only able to escape the IS-held city by telling the fighters at checkpoints that they were traveling to another town under the extremists' rule.

"In the early dawn we tried to sneak out of the city, taking the small dirt roads," Abu Lina said, explaining the family ended up running into an IS checkpoint after taking a wrong turn. He said the fighters only let him pass because his mother is sick. She has a heart condition and needs to see a doctor, a service no longer available in Hit.

The civilians from Hit all spoke on condition that their full names not be used — fearing for the safety of extended family members still trapped in the IS-held city.

Despite territorial gains in Anbar by Iraqi government forces, few families have been able to return home. The United Nations estimates that of Iraq's more than three million displaced people, more than 40 percent are from Anbar province.

"Honestly we don't know what will be next for us. God willing, Hit will be liberated soon," Abu Lina said.