Nasserist politician Hamdeen Sabbahi has said he welcomes the presidential candidacy of former army chief Abel-Fattah El-Sisi.
The field marshal, who led the ouster Egypt's first freely elected leader Mohamed Morsi after mass protests last summer, announced on Wednesday he would stand for president, ending months of speculation.
Sabbahi, who came third in the 2012 election that Morsi won, is the only other declared contestant for the country's top post.
"I welcome El-Sisi's candidacy. We look forward to democratic, fair and transparent elections that guarantee the impartiality of the state and the people's right to choose a president with their free will," Sabbahi said early on Thursday via Twitter.
In an address on state TV on Wednesday night, El-Sisi said he was "not going to launch a traditional presidential campaign" and vowed he would "continue to fight every day for an Egypt free of fear and terrorism," in reference to an Islamist insurgency that has been growing since Morsi's removal.
A spokesperson for Sabbahi's presidential campaign, Masoum Marzouk, said his candidate should also have an opportunity to speak on state TV, Al-Ahram Arabic news website reported.
El-Sisi, 59, who had to resign from his posts of army chief and defence minister in order to stand in the poll, is expected to secure a landslide victory.
He is widely viewed as the country's saviour and the strong leader needed to restore stability after three years of political tumult since the 2011 uprising that ousted autocrat Hosni Mubarak.
Commenting on El-Sisi's candidacy, Washington, a major donor of military aid to Egypt, said it did not support individual candidates or parties in Egyptian elections.
General Sedki Sobhi, formerly army chief of staff, replaces El-Sisi as head of the army.
"As the election process moves forward we urge the Egyptian authorities to ensure that the elections are free, fair, and transparent; that all candidates are able to campaign freely, without fear of harassment or intimidation; and that the views of all the Egyptian people are fully represented," White House National Security Council spokeswoman Bernadette Meehan said in a statement.