The president of Yemen agreed Wednesday to step down after 33 years in power.

Ali Abdullah Saleh signed an agreement aimed at ending a 9-month-old uprising in his country. He's the fourth Arab leader to be toppled after a series of protests this year in the Middle East.

Saleh agreed to transfer power to his vice president and promised his ruling party "will be cooperative" in working with a new unity government. The plan calls for elections within 90 days.

The United States pressed Saleh to step down over concerns that a security collapse in the Arab nation would give more power to al Qaeda.

Since February, thousands of Yemenis have protested across the nation, calling for democracy and the fall of Saleh's regime.