Speculation has been rife over whether the vastly popular Muslim Brotherhood, which has been outlawed since 1954, would anoint any of the hopefuls competing in the polls -something that would have been worth hundreds of thousands of votes.
Despite efforts from several aspirants to court its vote, the Brotherhood issued a statement saying it "could not support an oppressor or cooperate with a corrupt person or with a tyrant".
In recent days, the Brotherhood had kept many guessing about its position regarding the elections. One of President Hosni Mubarak's main rivals, al-Ghad party leader Ayman Nour, said he had sought the group's support.
The Brotherhood - which claims an active membership of two million and support from three more million across Egypt - said its decision came after it had analysed the political platforms announced by the different candidates.
Anyone but Mubarak
The statement, signed by group supreme leader Muhammad Mahdi Akef, did not name any of the candidates, but a leading member said it meant that Brotherhood members could still vote for any of the candidates except for Mubarak.
"The people should shoulder their full responsibility and should practise their constitutional and legitimate right to express their opinion ... and carefully examine their choice"
"It is unthinkable for us to decide to back Mubarak," Akef told the Al-Hayat daily on Saturday.
"The fact that he has ruled over Egypt for 24 years and has not
Mubarak, Egypt's leader since Anwar Sadat's 1981 assassination, is expected to easily win the upcoming polls.
introduced a single political reform over that period is enough justification," he added.
His government has cracked down repeatedly on Brotherhood members during his rule, sparking complaints of human rights abuses.
Meanwhile, Aljazeera reported that Mubarak held his first presidential campaign in the city named 10th of Ramadan.
He delivered a speech pledging job creation as well as democratic reform if he wins his fifth term.
"[My government would] create 700,000 job opportunities a year for our people entering the workforce year after year," the 77-year-old incumbent told a crowd of about 1000.
Mubarak also pledged to pursue constitutional amendments that "enshrine the liberties of the citizen, reinvigorate political parties" as well as draft an anti-terrorism law that "would serve as a legal substitute to the application for the emergency law".
He also vowed to revise detention laws, which currently allow for the extension of suspects' remand in custody for up to six months without charges being laid.
Mubarak has promised to create
Mubarak surprised many this year by calling for open elections to replace the previous system of a referendum for only the incumbent.
But opposition activists are criticising the polls as being unfairly weighed in his favour. At least two opposition groups have said they are boycotting the vote, arguing Mubarak enjoys unfair advantage.
There had been talk that the Brotherhood may even boycott the polls, but Akef said in the statement that participation of its members "has become a responsibility".
"Let's be keen on carrying it (the vote) out truthfully and in the way that our God likes," Sunday's Brotherhood statement said.
"The people should shoulder their full responsibility and should practise their constitutional and legitimate right to express their opinion ... and carefully examine their choice."
The seasoned grassroots political movement, which has survived consecutive Egyptian governments partly by treading a fine line in its confrontations with the government, is known for its ability to mobilise large numbers of its members.
The government banned the Brotherhood in 1954 but allows it to exist, although it tightens and relaxes its grip on the group as the political climate changes. The group renounced violence in the 1970s.
As an outlawed group, Brotherhood members may not run in elections, but it can endorse candidates. Fifteen Brotherhood-backed candidates form the largest opposition bloc in the outgoing parliament.