THE Muslim Brotherhood,Egypt's biggest oppositiongroup,willnot attempt to challenge the ruling party in the 2011 presidential election under the existing constitution, its leader told Reutersin an interview.The group is officially banned, forcing supporters to contest elections as independents. But the hurdles set by the constitution makeitvirtually impossibleforanyindepen- denttorunfor presidentagainstthecandidate backed by President Hosni Mubarak's party.Brotherhood leader Mohamed Mahdi Akef told Reuters this week that his movement, which seeks to establish an Islamic state by non-violent means, would not make an electoral show of defiance."There are a lot of preparations that need to be addressed (before discussing) a presidential nomination, and at the fore- front are freedom and a clean constitution," Akef said. Reiterating theBrotherhood's position that it did not want open confrontation with the state, he said."I made my own calculations. Should I go by force and clash with the regime? I say no, we don't do that." The Brotherhood, which renounced vio- lencelong ago,isseenas theonlygroupable to muster hundreds of thousands of disci- plined supporters against the Government, but analysts say it fears sparking a crack- down that could crush it.It controls about a fifth of the seats in parliament's lower house through supporters who ran in 2005 as independents.The authorities have since obstructed its efforts to build on those gains in municipal councils or the upper house, and frequently arrest Brotherhood members.Mubarak, 81, and in power since 1981, has not said whether he will run in 2011.His silence has fuelled speculation about a successor with the spotlight on his 46- year-old politician son Gamal. However, officials say the succession is not on the agenda of a ruling party conference this weekend. Akef said if Gamal, who unlike most presidents of Egypt has no military background, became president, he would be beholden to the security forces.