BAGHDAD — Thousands of supporters of an influential Iraqi Shiite cleric took to Baghdad streets on Friday following his demands for government reforms, pushing through security checkpoints and surging over a bridge on the Tigris River to set up a sit-in outside the Green Zone, the heavily secured government compound.

The demonstrations catapulted Muqtada al-Sadr to the forefront of what only six months ago was an impassioned — albeit mostly secular — movement demanding reforms, an end to corruption and greater accountability by officials in power.

Though al-Sadr, who lives in the southern holy city of Najaf, was not out on the streets, the cleric appears to have taken over the protest movement, sidelining secular reformists for sectarian politics.

“Yes, yes, our leader is al-Sadr,” chanted the protesters outside the walls of the Green Zone where they set up camp. As night fell, police did not move against the protesters or dismantle their encampment.

Earlier Friday, the protesters pushed through security lines, cut coils of barbed wire and surged over a bridge on the Tigris to reach the outer walls of the Green Zone, the fortified complex home to the country's political elite, foreign embassies and the government headquarters and which al-Sadr has labeled a “bastion of support for corruption.”

Just over six months ago similarly large crowds of impassioned Iraqis were also calling for an end to corruption and greater accountability, but with different language, appealing to the country's nationalistic sentiments rather than specific leaders.

Al-Sadr's protests are “co-opting and wrecking what remained of the genuine anti-corruption, pro-reform protest movement,” said Kirk Sowell, publisher of the Inside Iraqi Politics newsletter. The move, Sowell argues, is further fracturing a political system already paralyzed by sectarian strife.

Last summer, at the height of a spontaneous, secular protest movement, Iraqi Prime Minister Haider al-Abadi proposed reforms that he pledged would address corruption and mismanagement. His proposal was quickly backed by Iraq's parliament and the country's influential Shiite clerics, handing the newly appointed Iraqi leader a powerful mandate.

But in the following months Iraqis witnessed few changes, and al-Abadi's support began to crumble. On the Iraqi streets, the protests fizzled out.

Iraqi politicians and analysts blame al-Abadi's failure on the leader's own missteps, but also on the U.S.-imposed confessional system of government and party quotas that have dominated Iraqi politics after 2003 and encouraged sectarianism.

In February, al-Sadr demanded Iraqi politicians be replaced with more technocrats and that the country's powerful Shiite militias be incorporated into the ministries of defense and interior. The following weeks he called on his supporters to begin to take to the streets, and each Friday their numbers grew.