Already in political crisis, the Iraqi government moved to arrest Shia protesters who had stormed parliament and occupied the building, sending lawmakers fleeing for their lives.

The protesters want an end to the US inspired political system that awards offices and seats on a religious basis. They are led by an old "friend"; Radical Shiite cleric Moqtada al-Sadr, who inspired an uprising against US forces in the early days of the occupation.

BBC:

Supporters of cleric Moqtada Sadr broke through barricades of the fortified Green Zone for the first time, after MPs failed to convene for a vote.

A state of emergency was declared and security forces near the US embassy fired tear gas.

Protesters set up camp outside the parliament after occupying the chamber.

Nearby foreign embassies are watching anxiously but there has been no serious violence so far.

"We still view this as a demonstration," Sabah al-Numan, spokesman for the counterterrorism forces, was quoted as saying by the Associated Press news agency. "We aren't taking any part in this as it's not something regarding terrorism."

Mr Sadr wants Prime Minister Haider al-Abadi to commit to a plan to replace ministers with non-partisan technocrats.

Powerful parties in parliament have refused to approve the change for several weeks.

Earlier this week, hundreds of thousands of people marched towards the Green Zone, the most secure part of Baghdad that houses embassies and government buildings, to protest against the political deadlock.

Iraqi President Fuad Masum has called on the protesters to vacate parliament and politicians to enact the cabinet reshuffle.

A new protest outside the zone escalated after parliament again failed to reach a quorum on Saturday.

Groups marched on the district soon after the end of a televised appearance by Mr Sadr, although he did not call for the storming of parliament.

While the policy being protested - that there would be a careful division of power among Shias, Sunnis, and Kurds - was originally created by the Bush administration, it has led to massive corruption and government gridlock. 

The Obama administration's premature pullout has now resulted in a political crisis that may bring down one of our only allies in the Iraqi government.

Washington Post:

President Obama’s plan for fighting the Islamic State is predicated on having a credible and effective Iraqi ally on the ground in Prime Minister Haider al-Abadi.

And in recent days, the administration had been optimistic, despite the growing political unrest in Baghdad, about that critical partnership.

But that optimism — along with the administration’s strategy for battling the Islamic State in Iraq — was thrown into severe doubt after protesters stormed Iraq’s parliament on Saturday and a state of emergency was declared in Baghdad. The big question for White House officials is what happens if Abadi — a critical linchpin in the fight against the Islamic State — does not survive the turmoil that has swept over the Iraqi capital.

The chaos in Baghdad comes just after a visit by Vice President Biden that was intended to help calm the political unrest and keep the battle against the Islamic State on track.

As Biden’s plane was approaching Baghdad on Thursday, a senior administration official described the vice president’s visit — which was shrouded in secrecy prior to his arrival — as a “symbol of how much faith we have in Prime Minister Abadi.”

After 10 hours on the ground in Baghdad and Irbil, Biden was hurtling toward his next stop in Rome. The feeling among the vice president and his advisers was that Iraqi politics were on a trajectory to greater calm and that the battle against the Islamic State would continue to accelerate. Some hopeful advisers on Biden’s plane even suggested that Abadi might emerge from the political crisis stronger for having survived it.

No one is talking that way now. “There’s a realization that the government, as it’s currently structured, can’t hold,” said Doug Ollivant, a former military planner in Baghdad and senior fellow at the New America Foundation. “It’s just not clear how the Iraqis get out of this. I just don’t see how they will.”

A collapse of the Iraqi government would be catastrophic. It is possible that Iran would step in to maintain order and, coincidentally, place a Shia in charge who would be compliant with Iran's wishes. If Iraq wasn't a satellite of Iran, it most definitely would be under those circumstances.

What passes for mainstream Iraqi politics cannot deal with this crisis. They have no real base of support and have relied on American aid to maintain their position. It is probable that this won't work anymore. The next few days will be critical in determining Iraq's fate.