The former international footballer George Weah will run for president of Liberia for a second time.
He said he had the "vision" to transform the country.
Mr Weah, who played for teams including Paris Saint-Germain, AC Milan and Chelsea, was the highest-ranking African footballer in Fifa's list of greatest players of the 20th century.
His previous presidential bid, in 2005, was defeated by current president Ellen Johnson Sirleaf.
Her second term in office will end in 2017 and under the country's constitution she cannot run again.
During his football career, Mr Weah became a UN goodwill ambassador.
Later he turned to politics. He is currently a senator for the western province of Montserrado, which includes the capital Monrovia.
In 2011 he ran for vice-president under Winston Tubman but did not win.
Mr Weah belongs to the opposition Congress for Democratic Change (CDC) party.
Announcing his presidential bid in Monrovia, he said he had been a "victim of poverty" like many of his supporters, and said he would boost vocational education.
Anthem and portraits - Jonathan Paye-Layleh, BBC News, Monrovia
Liberia's national anthem was played before Mr Weah took to the stage.
First, he held a moment of silence in memory of the thousands of people who died of Ebola.
He told his crowd of supporters: "Our gathering here today is about the future of our country and our people.
"In the last ten years our people have continued to live in abject poverty, education a mess, health delivery system a disaster, electricity and pipe-borne water elusive."
"Like many of you, I have been a victim of poverty," he said. "There were times I didn't have school fees."
A leading research organization has recently rated Mr Weah's performance in the Senate as low.
Party members from across Liberia presented a petition asking him to run, saying they believed he was the man "to solve Liberia's numerous problems".
Some party members paraded up and down the sandy party headquarters, beneath giant portraits of Mr Weah.
They sang: "George Weah is the man we want, George Weah is the man we want."
Mr Weah pledged to increase the national budget, work towards religious harmony, and support vocational education.
To wild applause, he said: "God is with us, and hope is alive."