The Salafist Nour Party demanded that the criteria set by the presidency last week for selecting the 50-member committee which will finalise amendments to the suspended 2012 constitution be revised.
The ultra-conservative party also rejected attempts to tamper with the "Islamic identity of Egypt" during the amendment process.
In a statement issued on Monday evening, the Nour Party rejected the presidency's allotment of only five seats in the committee to political parties, charging that limiting the participation of parties in deciding the country's future mimicks Mubarak's policies which marginalised all players outside of his own NDP.
The Nour Party, a one-time ally of the Muslim Brotherhood, had agreed to the roadmap for political transition announced by the army on 3 July after the ouster of Mohamed Morsi.
That map included the suspension of the Islamist-backed 2012 constitution pending amendment by a broadly-representative committee.
The party on Monday reiterated its stand against amending articles regarding Egypt's "Islamic identity," in reference to its defence of article 221 of the suspended constitution.
Since 1971, the Egyptian constitution has broadly stated that the "principles of the Islamic Sharia are the main source of legislation," leaving it up to courts to interpret those principles.
However, article 221, which was pushed by Salafists during deliberations on the suspended charter, offered a more strict interpretation of the "principles" of Islamic Sharia by broadening the source of those principles to the Quran, the sayings of the Prophet, and the interpretations of the four main Sunni schools of Islamic jurisprudence, thus giving courts less leeway in interpreting what constitutes "principles."
The statement argued that only those articles which "urgently" require amending are powers granted to the president and prime minister, or election laws, and not article 221.
Nevertheless, the statement assured that the Nour Party will participate in the 50-member committee despite its reservations.
On Thursday, Nour spokesperson Nader Bakkar had said in a televised interview with CNN that his party will reconsider its support for the army-backed political roadmap if the constitutional committee changes Article 221 of the 2012 constitution.
Bakkar confirmed during the interview that all those participating in transitional roadmap have agreed to preserve the Islamic identity of the state.