Members of the two chambers of parliament pray during a meeting to elect a 100-member constituent assembly in Cairo on Tuesday. Criticising the blueprint for the division of the seats in the 100-member body due to be picked on Tuesday, groups including the liberal Free Egyptians Party said they would not take part at all and instead would hand their seats to women, Christians, workers, peasants and others - sections of society they said had been denied representation. (STRINGER/EGYPT/REUTERS)

After marathon negotiations that exposed the deep rift between ascendant Islamist parties and the country’s secular forces, Egyptian lawmakers on Tuesday night appointed a panel that will draft the country’s new constitution.

Several liberal and secular parties boycotted the process, saying that Islamists would be overrepresented in the 100-member Constituent Assembly. Their absence raised the prospect that many Egyptians will question the validity of the document the panel produces.

The establishment of a new charter is among the most important elements of Egypt’s transition to democratic rule, coming after the three-decade reign of autocratic President Hosni Mubarak and the turbulent period of military rule since his ouster on Feb. 11, 2011.

Among other things, the new constitution is expected to outline the powers of the presidency and parliament in post-revolutionary Egypt. It also will determine the extent to which Islamic law will be the guiding source of lawmaking and governance.

Liberal politicians questioned Tuesday night whether the body would be seen as legitimate.

“I don’t think this is representative of the country,” said Mohamed Abou el-Ghar, the founder of the Egyptian Social Democratic Party, one of the groups that walked away from the process. “It is not representative of the different ideas, the different minorities. I don’t know how it will work.”

The Muslim Brotherhood, the dominant bloc in parliament, had said it was committed to the formation of a representative body. In the end, though, liberals felt that the Islamist group and lawmakers from the dogmatic Salafist Nour party were trying to stack the charter-writing committee with conservatives. The names were released late Tuesday on the Web site of the Brotherhood’s Freedom and Justice Party, but the list did not include complete biographical information, making it hard to immediately gauge its members’ political leanings.

The body has six months to draft a constitution that will be submitted to voters in a referendum.

The first attempt to form a panel failed in April amid similar bickering. This time, lawmakers were acting under pressure from Egypt’s military rulers, who gave them a deadline to finalize the process. Failure to do so would lead to constitutional amendments made unilaterally by the generals or reactivation of the Mubarak-era constitution, the junta leaders warned.

The showdown has played out on the eve of a runoff presidential election scheduled for Saturday and Sunday. On Tuesday, the youth movement April 6 endorsed Mohamed Morsi, the Muslim Brotherhood’s candidate, whom the group sees as the lesser of two evils. April 6, which played a key role in last year’s popular revolt, is staunchly opposed to the candidacy of Morsi’s rival, Ahmed Shafiq, a former air force chief who served as Mubarak’s last prime minister.

Special correspondent Ingy Hassieb contributed to this report.