Cairo, Egypt (CNN) -- A Muslim Brotherhood candidate for next month's presidential elections here lashed out Monday at the eleventh-hour entrance into the race by Omar Suleiman, the former spy chief to deposed strongman Hosni Mubarak.
"We are not against the concept of anyone running as long as he has the right legal status, but it's unacceptable to have one of the symbols of Mubarak's regime run for president," Khairat el-Shater told CNN. "The majority of Egyptians will not accept him. His candidacy is an insult to the revolution."
The only way Suleiman could win would be by forgery, el-Shater said. "If there is a 1% chance of forgery in the elections, and he wins that way, then all the Egyptians -- not just the Muslim Brotherhood -- will take to the streets."
Elections are scheduled to start May 23.
El-Shater said the brotherhood's political arm, the Freedom and Justice Party, would respect "all signed treaties," including the 1978 Camp David Accords with Israel. "Regardless of any opinion toward these treaties, they were accepted by decent entities in the country, and it does not mean that changing the political system will affect the treaties."
But he noted that the accords included a component "about respecting the rights of Palestinians. The Egyptians respected their part of the deal but the Israelis -- until now -- have not respected the Palestinian rights. The Egyptians complied, but the Israelis did not."
El-Shater said the timing of a loan from the International Monetary Fund to the Egyptian government could prove problematic. "The timing is the problem because we don't think this interim government is performing well, so we object that they take this loan and spend it in two months, then the new government worries about paying it back."
Whatever happens in the election, the top priority for the Muslim Brotherhood and the Freedom and Justice Party is to ease sectarian tensions, which built under Mubarak's regime, he said. "Mubarak's former regime really oppressed the Coptics and the Muslims because his system was based on tyranny. We aim to rebuild our nation again."
Suleiman entered the race just hours before the Sunday deadline, said Hatem Bjato, who heads the election committee.
Suleiman had initially said he would not seek the presidency in the first election for the post since the revolution that led to the toppling of Mubarak. But on Friday, Suleiman did an about-face, saying he felt obliged to supporters.
"I promise you, my brothers and sisters, to complete the goals of the revolution and provide security and stability to the Egyptian people," he said in a written statement Friday.
Parliament, which is 70% Islamist, passed a bill against Suleiman's running. But it is only symbolic, said Zakaria Abdel Aziz, the former head of the lawyer's association. "Only a decision from the administrative court would execute such a ban," he told CNN. "Banning former regime members from practicing their political rights for five years or even 10 has been discussed thoroughly, but the law has not been reactivated and there must be proof that Omar Suleiman has been implicated in political corruption before he is banned from running."
The status of another candidate was less certain.
A court ruled that liberal opposition leader Ayman Nour will not be allowed to compete because he was jailed in recent years, the candidate's son said Saturday. Nour was recently pardoned and plans to appeal, the son said.
That decision could affect the future of al-Shater, since he too was pardoned for his past convictions.
A millionaire businessman who served two prison terms under Mubarak, al-Shater is considered a conservative, though he is also credited as being the driving force behind the Brotherhood's affirmation that Egypt should continue to honor its international agreements.
Fearful for the future of its candidates, the Muslim Brotherhood nominated Saturday an alternative, Mohammed Morsi, chief of the Freedom and Justice Party. "We are protecting the revolution and all of its goals. ... We have decided as the Brotherhood and its party to nominate Mohammed Morsi as our backup candidate for president," it said in a statement.
The group had pledged repeatedly that it would not field a presidential candidate. But candidates from its political arm won the largest share of seats in Egypt's parliamentary elections in December. And Brotherhood leader Mohamed Badie has said the new Egypt "is under a serious threat" because its current military-led government "has failed to represent the will of the people."
A military junta took power after Mubarak's ouster.
Salafist candidate Hazem Abu Ismael was also disqualified from running in the election because of his mother's U.S. citizenship, state television reported Saturday.
The deceased mother of Abu Ismael held U.S. citizenship and used her U.S. passport to enter Egypt three times, Egypt's Interior Ministry has said.
Ismael had said that his mother held a green card residency permit but was not a U.S. citizen. He told a private Egyptian TV program that his sister was married to an American and had obtained U.S. citizenship, but that his mother had not. The official number of candidates is 23.