CAIRO (Reuters) - The Muslim Brotherhood candidate for Egypt's presidency was cheered on by supporters on Thursday when he registered to run in an election where his main rivals will be other Islamists and candidates who served under the ousted president, Hosni Mubarak.
Khairat al-Shater, 61, a millionaire businessman and leading strategist in the Brotherhood, was named as its candidate last week in a policy reversal by the group that previously pledged it would not participate.
The Brotherhood's broad grass-roots network, built over decades, ensures Shater is a frontrunner, although he has yet to launch his campaign. "The people want Shater for president," the group of about 2,000 supporters chanted. Some lit fireworks.
"This is a historical day for Egypt. Our earlier decision not to field a candidate was for Egypt and its protection. Today, our decision to field a candidate is also for Egypt's benefit and out of a sense of responsibility" Saad Husseini, a member of the Brotherhood's party, told reporters.
Shater's bid for the presidency risks splitting the Islamist vote between him, a candidate who follows the stricter Salafi interpretation of Islam and another contender with more moderate views who was expelled from the Brotherhood over his decision to run before the group changed tack on fielding a candidate.
That could hand the advantage to two other main contenders: Amr Moussa, the former head of the Arab League who had also served as Mubarak's foreign minister in the 1990s, and Mubarak's last prime minister, Ahmed Shafiq, who, like the ex-president, was once in charge of the air force.
In a poll researched in March, just before Shater was named as a candidate, Moussa was frontrunner with the Salafi candidate Hazem Salah Abu Ismail in second place, and Shafiq third. Islamists already dominated parliament.
Abu Ismail's campaign said after Shater was nominated that it would make their candidate "more popular".
But his campaign has also had to fend off accusations that his late mother was a U.S. citizen, which would disqualify him from a race that stipulates both parents must be only Egyptian, with no dual citizenship.
The website of state-run Al-Ahram newspaper on Thursday cited the head of the Higher Presidential Election Commission as saying it had received a letter from the Interior Ministry that said Abu Ismail's mother had travelled using an American passport three times in the five months before she died in 2010.
Campaign manager Mohamed Nasr said Abu Ismail had filed a lawsuit that would force the Interior Ministry or the commission to show she had only Egyptian nationality, adding the media talk was "entirely fake".
The door for nominations closes on Sunday with any challenges to nominees reviewed after that. About 1,000 people have take documents to register to run. The first round of voting is May 23-24, followed by a second round on June 16-17.
Fears that Shater's candidacy could hand power to those outside the Islamist camp has prompted some groups to call for a single Islamist candidate to run and for others to step aside. None of the main contenders have yet indicated they would.
The rise of Islamists is being closely watched in the West, long wary of their influence in Egypt, the first Arab state to make peace with Israel and recipient of $1.3 billion in annual U.S. military aid. But U.S. and other officials have lined up to meet Brotherhood officials, including Shater.
In his first reported comments since he was named, Shater, a pragmatic conservative, pledged to introduce sharia, Islamic law, as his "first and final" objective if elected and also pledged to reform the Interior Ministry.
He also dismissed suggestions that he had connived with the military, which has ruled Egypt since Mubarak was ousted on February 11, 2011, to undermine the popularity of other Islamists.
The Brotherhood's Freedom and Justice Party, which controls the biggest bloc in parliament, has demanded the army-appointed government be sacked, criticising it for mishandling the economy and failing to reform the Interior Ministry and its police force. The ruling military council has rejected this.
Shater, jailed in 2007 by a military court and released before the end of his sentence and shortly after Mubarak was ousted, could be barred from running due to that jail term. But Brotherhood lawyer has said he was pardoned, although no official announcement has been made.
Essam Darbala, head of one Salafi body, the Consultative Council of the Islamic Group, said such issues raised concerns that Islamists could be excluded, leaving the field open to candidates such as Moussa and Shafiq.
"There will be great difficulty in transferring power from the military which has ruled Egypt for 60 years to civilians at the end of June," Darbala said in a statement.
The army has insisted it will not have a political role in the presidential vote and has vowed to stick to its pledge to hand power to the new president by July 1. Analysts expect it to wield influence from behind the scenes for years to come.
One potential candidate who some speculated could have the army's backing, Omar Suleiman, the former intelligence and who was briefly appointed at Hosni Mubarak's vice president, said he would not run in a statement, Egypt's official news agency said.
An aide to Suleiman, who asked not to be named, confirmed this to Reuters adding: "Pressure on him to (run) comes from various groups that do not represent him officially."
Some of his supporters earlier said they had gathered thousands of signatures needed for him to register.
Independents need to secure 30,000 backers from around the nation or support from 30 members of parliament. Any party represented in parliament can field one candidate.
Moussa and Shafiq have exchanged barbed remarks. According to the daily Al-Masry al-Youm, Moussa said it would be wrong for the first president after Mubarak's to be the ex-president's last prime minister. "Egypt needs deep-rooted change," he said, the newspaper reported.
In counter comments, Shafiq said Moussa secured the post of Arab League chief because he was picked by Mubarak. Arab states vote on the secretary-general but the post has almost always been held by an Egyptian.
Additional reporting by Yasmine Saleh; Writing by Edmund Blair; Editing by Alison Williams