A politician expelled from the Muslim Brotherhood is finding support among liberals and Islamists alike in his bid for Egypt's presidency, challenging the group he helped lead with a message that spans divisions in a polarized society.

Abdel Moneim Abouel Fotouh is appealing to a broader constituency than many of the candidates in a field that includes a Brotherhood leader and former members of the Hosni Mubarak administration. Whether he can win the historic democratic election will depend on how deeply that support runs.

His chances were improved by the disqualification of leading Islamists including the Brotherhood's first-choice candidate and an ultra-orthodox Salafi preacher who were both contenders.

Egyptians go to the polls in May to decide who will replace Mubarak – toppled last year after decades of repressive rule – as head of the Arab world's most populous state.

The vote is expected to go to a June run-off between the top two candidates. Former Arab League chief Amr Moussa is seen as another of the front-runners.

Though Abouel Fotouh was ejected from the Brotherhood last year – he defied its wishes with his presidential bid – analysts believe he still commands broad respect in a group that he helped lead for several decades. Since parting ways with the Brotherhood, his appeal has gone well beyond the Islamist camp.

His commitment to political reform has impressed secular-minded Egyptians. Some of Mohamed ElBaradei's backers have rallied to his side after the reformist liberal quit the race.

Beyond the elite, a reputation for honesty and consistency is helping Abouel Fotouh build a following among the population at large.

"What he says, he does," said Amr el-Shobaki, an independent member of the Egyptian parliament, extolling Abouel Fotouh's virtues as he introduced him at a rally in a working class district of Cairo on a Thursday evening in April.

Abouel Fotouh, he said, was the right man to "break the polarization" of a country where rifts have deepened between Islamists who dominated parliamentary elections and others for whom the rise of the Brotherhood is a cause of deep concern.

Abouel Fotouh, a 60-year old doctor, loosened his tie as he stood to address the crowd of several hundred people. They listened quietly as he outlined a vision that would make Egypt a G20 economy in 10 years, strengthen its army and eradicate remnants of the autocratic old order whom he described as a major threat.

"After the January  25 revolution, God willing, the Egyptian people will no longer dream simply of their rights. They will dream of something more than that," he said.

Egypt, he said, must be run by a civilian state that respects Islamic law in a moderate form, "far removed from secular, Islamic or religious extremism". "Egypt will not be a copy of Turkey, or Tunisia, or Iran," he said, listing states governed in full or part by Islamists. "Egypt will be Egypt."

Undecided voters

"He is a respectable person and a moderate. The Egyptian people need this idea at this time," said Murad Fakhri, one of a group of ultra-orthodox Salafi Muslims who were watching Abouel Fotouh speak. Khaled Badr, another Salafi in the crowd, said he had planned to vote for Hazem Salah Abu Ismail, the disqualified preacher, but would now vote for Abouel Fotouh instead.

While opinion polls have shown Abouel Fotouh trailing candidates including Moussa and Abu Ismail, many voters have yet to make up their minds. Abu Ismail's elimination leaves his Islamist supporters with the choice of Abouel Fotouh and Mohamed Morsy, the Muslim Brotherhood candidate who has described himself as the only Islamist in the field.

Mahmoud Hussein, the group's secretary-general, was dismissive of Abouel Fotouh's chances, saying that while many liberals were still concerned about his Brotherhood past, many Islamists had started to doubt he was a true Islamist. "He will get some votes from here, and some from there," he told Reuters.

Yet Abouel Fotouh's past is inextricably linked to the Islamist group banned under Mubarak. He was part of a reformist wing that Brotherhood watchers say has been marginalized by the more conservative elements which now run the group.

His Islamic activism evolved on campus. He is famous for publicly confronting President Anwar Sadat in the 1970s, telling him he was surrounded by hypocrites. A recording of the heated debate has been posted on an Abouel Fotouh campaign web site.

Sadat jailed Abouel Fotouh along with hundreds of other dissidents in 1981. In a new book, Abouel Fotouh recalls finding himself in prison alongside the likes of Ayman al-Zawahiri, now the leader of al Qaeda, and other more radical elements rounded up after Sadat was assassinated by Islamist gunmen that year.

Abouel Fotouh's confrontation with Sadat is cited by his new supporters as one source of admiration. While Abouel Fotouh is gaining from a perception that he is a man of principle, the Brotherhood is struggling against claims that it has grown power hungry – something fiercely denied by the group.

"The very cool thing about Abouel Fotouh is that once you hear about him, you are sold," said Waleed Abd el-Rahman, a 27-year old business development manager who like most Egyptians was not involved in politics during the Mubarak era.

"All the things he talks about are very inclusive. You wouldn't feel left out by him whether you were an Islamist, a liberal, a Christian or even if you don't believe in God."