The Nour Party, Egypt’s main Salafi bloc and the second-largest winner in last year's parliamentary elections, will publicly back the country’s draft constitution and urge its supporters to vote yes, despite an amendment that could lead to the party being banned, a senior member has said.

The decision, which will be officially announced at a press conference on Thursday, removes one of the main potential sources of opposition to the draft, which is due to go before a public referendum in late December or early January. Many of Egypt’s liberal parties have already announced their support.

With Nour on board, the only serious organised opposition is likely to come from supporters of deposed president Mohamed Morsi and his Muslim Brotherhood. Several revolutionary groups, including the April 6 movement and the Revolutionary Socialists, have also rejected the draft, but they command limited popular support.

“It is below our expectations, but generally speaking it is acceptable for us to say yes to these amendments, rather than to say no,” Nader Bakkar, a co-founder of the Nour party and its spokesman, told Al Jazeera in an interview on Wednesday.

Nour will endorse the draft despite a weakening of the amendments on Egypt's "Islamic identity," which were a main priority for the party's representative on the 50-member committee that drafted the constitution.

Article 74 would prohibit political parties formed “on a religious basis,” which could be used to ban the Brotherhood’s Freedom and Justice Party. A similar ban was in force during President Hosni Mubarak’s 30-year rule.

Analysts say Nour is less likely to be affected, because it backed the political "road map" presented by the army after it overthrew Morsi in July. Bakkar denied any kind of deal, but acknowledged that the article is likely to be applied in a political fashion.

“The issue is not the article, but the use of the article,” he said.

'We have to advise'

Bakkar also criticised language in the constitution that could reverse the order of elections scheduled for next year.

The road map called for parliamentary elections in early 2014, followed by a presidential ballot in early summer, but the constitution allows interim President Adly Mansour to call for a presidential ballot first.

Committee sources say the provision was added by members anxious that Egypt’s weak political parties will not be ready for parliamentary elections by springtime.

Officials in Nour are worried, Bakkar said, that the amendment “could open the door” to other changes.

Local newspapers have reported in recent days, citing military sources, that the road map could be delayed and Mansour asked to remain in office, though the interim cabinet has denied those reports.

Nonetheless, Bakkar said that not even a change in the electoral calendar would compel Nour to withdraw its support for the interim government.

"Honestly speaking, what can we do? Withdraw from the political scene? A lot of people would say, you’re welcome to, go away," he said.

"We have to advise, to criticise, to make some kind of pressure behind closed doors, but nothing else."