Nobel Peace laureate Mohamed ElBaradei, former head of the UN nuclear watchdog, is awaited in Cairo as police warn his supporters not to mark the homecoming of a would-be electoral challenger to President Hosni Mubarak.
ElBaradei, who is expected to fly home on Friday, has repeatedly called for democratic change in Egypt since stepping down as head of the International Atomic Energy Agency in November.
On the eve of his return, he reaffirmed his determination to "do everything I can for Egypt to advance toward democracy and economic and social progress."
"I hope to be an instrument for change," the 67-year-old long-time international civil servant said in an interview with Egypt's Dream TV.
"I am ready to throw myself into Egyptian political life on the condition that there are free elections, and the first step toward that would be a constitutional amendment under which I can be a candidate and others as well."
ElBaradei's supporters await his return (Photo: AFP)
Mubarak, 81, will complete his fifth term in office next year and his son, Gamal, is often cited as his potential successor.
At the moment, the constitution effectively bars an ElBaradei candidacy.
It requires that a candidate have been for at least one year a leading member of a party that has been in existence for at least five years. Such is not the case with ElBaradei.
And for him to run as an independent, he would have to be endorsed by at least 250 elected officials, including 65 members of the National Assembly, 25 members of the Consultative Council (senate) and 10 members of municipal councils.
All those bodies are dominated by Mubarak's ruling National Democratic Party.
First, of course, ElBaradei must return home, and security sources have told AFP that measures would be taken to prevent any "illegal demonstrations" by his supporters at Cairo airport.
Two members of the April 6 Movement opposition group, Ahmed Maher and Amr Ali, have already been arrested for organizing a reception for ElBaradei and distributing leaflets encouraging people to attend, Egyptian media reported.
Since November, ElBaradei has pointedly refused in newspaper interviews to rule out standing in next year's presidential election against Mubarak, who has been in power for 29 years.
Despite the difficulties facing his standing for Egypt's top job, the very possibility of his candidacy has triggered a vicious campaign against him in the official press.
State-owned dailies have accused him of being out of touch with the nation's affairs after his long years working abroad.
ElBaradei left Egypt 27 years ago to work for the United Nations. He headed the IAEA for 12 years until his retirement.