By Shaimaa Fayed and Edmund Blair
CAIRO (Reuters) - Tens of thousands of Egyptians demanded on Friday that their military rulers stick to a pledge to hand over power by mid-year after a row over who can run in the presidential election raised doubts about the army's commitment to democracy.
Two leading Islamist candidates, one representing the Muslim Brotherhood who was seen as the frontrunner, were among those disqualified this week from a vote that starts on May 23-24, drawing a storm of criticism from supporters and the candidates.
Khairat al-Shater, the Brotherhood's former candidate, said his ejection showed the generals who have ruled since Hosni Mubarak was ousted last year had no serious intention of quitting. The movement is now fielding a reserve candidate.
"We are all here to protect the revolution and complete its demands," said Sayed Gad, 38, a pharmacist and Brotherhood member. He had joined a protest which attracted both Islamists and liberals to a packed Tahrir Square in central Cairo.
A council of generals, who stepped in 14 months ago after mass demonstrations in Tahrir and elsewhere sapped Mubarak's power, has led Egypt through a turbulent transition punctuated by spasms of violence and frequent protests against their handling of the move to democracy.
The army says it will stick to its timetable to hand power to a new president by July 1 and has promised to oversee a fair vote. But some remarks from military officials suggesting the army might also seek now to have a new constitution in place before that handover - an impossibly tight deadline for many - has added to popular worries about the military's ambitions.
Western diplomats expect the timetable for transferring powers to hold but say the army which supplied Egypt's presidents for six decades, including Mubarak, and which has built up sprawling business interests throughout that time, will remain an influential player behind the scenes for years.
"Down with military rule" and "The people want the execution of the marshal," some protesters chanted, a reference to Field Marshal Mohamed Hussein Tantawi, Mubarak's defense minister for two decades who now leads the ruling military council.
Some demonstrators sheltered under awnings and umbrellas to shade them from the midday sun. Many waved Egyptian flags.
Thousands also gathered in the second city Alexandria and turned out in some other cities. The hours after weekly prayers at mosques on Fridays are traditional times for protests.
Another candidate, Omar Suleiman, Mubarak's former spy chief and briefly his vice-president, was also ejected from the race. His candidacy had raised fears the army wanted to roll back gains made since last year's uprising, but there are still others in the race seen as vestiges of Mubarak's old order.
"No to remnants. No to military rule," read one banner that carried pictures of Mubarak's last prime minister Ahmed Shafiq, a former air force commander, and of Moussa, a former foreign minister. They are both strong contenders, especially now that the Brotherhood's Shater has been disqualified.
Friday's demonstration was the first in months to bring both Islamists and liberals together. Although broadly united in criticism of the army, their demands are not fully aligned. Liberals also fret about the strength of political Islam after Islamists - notably the Brotherhood and smaller, harder line Salafi movement - swept a parliamentary vote in December.
Rows over who is eligible to run for Egypt's first real presidential election in its history has added to tensions already running high over who should write the new constitution.
Liberals, as well as Christian and Muslim religious establishment figures, quit an assembly that was picked to draw up the new constitution because they said it was dominated by political Islamists and did not represent Egypt's diversity.
The assembly, appointed by the new, Islamist-dominated parliament, has now been suspended.
The April 6 youth group, which helped galvanize the anti-Mubarak demonstrations last year, had called for Friday's protests in part to demand that new criteria be laid down to ensure a diverse make-up for the constituent assembly.
Also among the protesters were supporters of Hazem Salah Abu Ismail, an ultra-conservative Salafi candidate for the presidency who had built up a big popular following but who was also disqualified from the race because his mother had U.S. nationality, violating one of the rules for holding the office.
From a stage in Tahrir Square where his supporters had also gathered on Friday, people chanted over loudspeakers: "Islamic revolution! With our soul and blood, we sacrifice for Islam!" and "The Koran is the constitution!"
(Writing by Edmund Blair)