LAST year, at the height of Egypt's revolution, I came across a makeshift casualty hospital set up in an abandoned shop in the backstreets near Tahrir Square in Cairo.

It had been established and staffed by volunteer doctors and nurses who were members of the Muslim Brotherhood and marked my first encounter with the movement about which, at the time, there was much speculation and some concern over their supposed militant credentials.

A little to my surprise, those Brotherhood members I spoke to that day left me with an altogether different impression. Their talk of the need for greater democracy and pragmatic assessment of the crisis then facing Egypt appeared to chime near perfectly with the aspirations expressed by most of their fellow Egyptians, who had turned Tahrir Square into a symbol of the hopes that lay at the heart of the Arab Spring.

Perhaps I should have been less surprised as to the Brotherhood's response.

After all, for a long time now the movement has displayed a pedigree that has ensured both its current and most likely future role for years to come as Egypt's most significant political player.

To its advantage, the Brotherhood's leadership is composed almost exclusively of long-time members – many of whom were active for years in pivotal organisations such as trade unions, religious charities and professional bodies under the previous regime of President Hosni Mubarak.

They were often persecuted under Mubarak's rule, many subsequently serving time as political prisoners.

As a result of this, the Brotherhood maintains a cohesion and sense of purpose that other Egyptian political groups have yet to achieve.

It also makes them disinclined to tolerate political rivals who, should they come to power, might generate a new era of repression against the Islamist movement.

This most likely goes some way to explaining why President Mohamed Mursi, himself a key figure in the Brotherhood, saw fit to pass a decree granting himself sweeping new powers – sparking protests across the country and leading to a stand-off with the justiciary.

Already, more secular, liberal, left-wing and Christian members have boycotted a constituent assembly set up to draft Egypt's new constitution and have accused the Islamists of trying to impose their vision.

But just why has Mr Mursi embarked on such a risky course of action? Well, firstly, he has forced the showdown with judicial authorities in order to pre-empt a potential ruling on Sunday by the Supreme Constitutional Court that would dissolve the constituent assembly and further delay the drafting process.

Another reason for Mr Mursi's move results from the pressure he and the Brotherhood find themselves under to regain Egypt's legislature before its own popular support wanes. Mr Mursi's presidency is being used to speed up the constitutional process, clearing the way for parliamentary elections which cannot be held until a constitution is approved by national referendum.

Motivating Mr Mursi, too, is a desire to take advantage of a split within the Salafists, the Brotherhood's main political opponents.

If the results from Egypt's last parliamentary elections, which were held in three stages between November 2011 and January 2012 are anything to go by, then the Brotherhood will likely win the majority in a new round of polls.

No single party appears able to challenge the Brotherhood, with the only possible threat coming from the Salafists, another Islamist group.

But far from being one cohesive party, the Salafists are instead made up of several groups which are often at loggerheads. These schisms are something the Brotherhood is keen to exploit before any future parliamentary elections.

According to some Middle East political analysts, including those at the independent global intelligence think-tank Stratfor, the longer Mr Mursi rules the more likely the Brotherhood's core support will wane.

This prediction is based on a number of factors, but perhaps the most significant is the economic pressure Egypt faces and the deadline Mr Mursi's government confronts in implementing economic reforms which are almost certain to be unpopular.

Riding out such a political storm would be easier if the Brotherhood were in a dominant position, controlling both the executive and legislature following elections.

Yesterday, Mr Mursi's government sought to keep the pace up as the assembly tasked with drafting the new constitution voted to keep the principles of sharia or Islamic law as the main source of legislation.

The problem with all this, though, is that as each of these constitutional changes are made, so the voices of dissent over the rapid-fire redrafting process become ever more vociferous.

Cracking on with such moves might be key to Mr Mursi and the Brotherhood's strategy, but coming as it does in a post-revolutionary Egyptian political climate – still brewing with anger, resentment, score settling and power-brokering – it is a risky business.

Should Mr Mursi prove to have miscalculated and overestimated the Muslim Brotherhood's power, then – unlike those revolutionary Tahrir Square days last year – the movement could well find itself on a very different side of Egypt's national divide.