Clashes erupted between followers of the ruling Islamist Muslim Brotherhood (MB) and the secular liberal and pseudo-left opposition on Tahrir Square in Cairo on Friday.

Fighting reportedly began after protesters chanted slogans against the MB and Egypt’s new president, Mohamed Mursi. The Islamists reacted by destroying a stage set up by the Popular Egyptian Current of Nasserite politician Hamdeen Sabahi and physically attacking their opponents. Clashes then broke out throughout the square and the surrounding streets, lasting hours.

In chaotic scenes protesters on both sides threw stones and Molotov cocktails at each other. Two microbuses used to carry Brotherhood members to the square were set ablaze. At one entrance of the square, the petty-bourgeois Revolutionary Socialists (RS) and the Muslim Brotherhood clashed as the RS tried to prevent the Islamists from entering the square. Throughout the day, dozens of protesters on both sides were wounded. Security forces were completely absent from the scene.

The clashes reflect mounting tensions inside the Egyptian political establishment over how to distribute power and influence inside the Egyptian state machine, after a revolutionary upsurge in the working class ousted long-time dictator Hosni Mubarak in February of last year.

One of the most contentious subjects of this internal struggle is Egypt’s new constitution. The Constituent Assembly, tasked with drafting the document, is controlled by the Brotherhood and the Salafist Nur Party who won the parliamentary elections in November last year. Secular groups criticize the Constituent Assembly for not representing the other political forces and social groups inside Egypt and demand a reshuffling or dissolution of the body.

Last Wednesday a partial draft of the new constitution was published, largely modeled after Egypt’s 1971 constitution but more tilted towards Islamic Sharia law. The secular opposition criticized it, and several lawsuits were filed against the assembly’s constitutionality. Next Tuesday Egypt’s Supreme Administrative Court is expected to rule on the validity of the assembly, possibly dissolving it and thus also voiding the proposed draft.

The court ruling will be another showdown between the ruling Islamists and the judiciary, which largely consists of Mubarak-era appointees. Already in June the High Constitutional Court ruled the People’s Assembly unconstitutional. It was subsequently dissolved by the then-ruling Supreme Council of the Armed Forces (SCAF) military junta.

After Mursi’s election and his counter-coup against SCAF, struggles inside the Egyptian ruling elite are again intensifying.

The Friday protests, dubbed “Accountability Friday,” were initially called by a broad coalition of liberal and pseudo-left groups, mainly to protest the Islamist-dominated Constituent Assembly. Some also criticized Mursi for failing to fulfill his promises in the first 100 days of his rule.

Participants included Mohamed El Baradei’s National Association for Change and his newly founded Constitution Party, Sabahi’s Popular Egyptian Current, the April 6 Movement, the Egyptian Social Democratic Party, the liberal Wafd Party, the Democratic Revolutionary Alliance (a coalition of various pseudo-left groups), and the Revolutionary Socialists.

On Thursday the Brotherhood, the Nur Party and other Islamist forces called for simultaneous protests on Tahrir Square against the acquittal of 25 Mubarak regime figures by the Cairo Criminal Court on Wednesday. The accused were charged with involvement in the so-called Battle of the Camels on February 2 last year—when Mubarak thugs attacked protesters on Tahrir Square in the initial days of the revolution. Mursi subsequently tried to remove Egypt’s prosecutor general Abdel Meguid Mahmoud, but backed down on Saturday.

Both groups, the ruling Islamists and the liberal or pseudo-left forces sought to present their Friday protests as “revolutionary.” But in fact neither of these camps expresses the interests of the Egyptian workers and youth, the main force behind the Egyptian revolution. They represent two factions of bourgeois Egyptian politics fighting over influence and positions inside the post-Mubarak state.

Neither camp has any significant popular basis amongst the working class, which increasingly views all the Egyptian bourgeoisie’s parties with contempt. The working class responded to calls for the Friday protests with a show of mass abstention. There is a sense amongst workers that the groups calling for protests are not fighting for the demands of the revolution.

Not long ago, the contending groups were collaborating closely against the working class. In the parliamentary elections last November, Hamdeen Sabahi and his Karama Party formed an electoral alliance with the Muslim Brotherhood. The RS supported Mursi in the presidential elections earlier this year, calling the Muslim Brotherhood a revolutionary force that could be pressured “to complete the objectives of the revolution.”

However the Brotherhood—now in power and in control of the presidency—is increasingly moving not only against the working class, but also against its former political allies.

The Islamists are clearly using these clashes to increase repression in Egypt. In a statement issued on Saturday, the Brotherhood declared that their members were attacked first and that the violence was committed by thugs. The statement demands “that the security forces arrest these criminals and put them on trial with all the other thugs facing prosecution.”

It also demands that all political forces “put the country’s interest above all personal and party interests and to hold the love for their country higher than the hate of the Brotherhood.”

The main target of the repression will be the working class. In the last weeks and months Mursi’s security forces repeatedly cracked down on protests and strikes of workers and youth, arresting hundreds. A recent report by the Nadim Human Rights Center revealed that at least 34 people were killed by the police in custody and at least 88 tortured in the first 100 days of Mursi’s rule.

The pseudo-left groups, which are now themselves coming under attack by the Islamists, are unable to mount any principled fight against the repression. Organically tied to the bourgeoisie and the state, they responded with impotent appeals to the Islamist government to intervene and protect them against the Islamist supporters on the streets.

On Saturday a coalition of the pseudo-left and liberal parties issued a statement calling upon Mursi to investigate the assault.

Amin Iskandar of Sabahi’s Popular Egyptian Current went even further, blaming the forces of the interior ministry for failing to protect the protesters. Their “neutrality” had only benefited the Muslim Brotherhood, he said.