SANAA, Yemen (AP) — Yemen’s autocratic leader agreed Wednesday to step down after months of demonstrations against his 33-year rule, pleasing the U.S. and its Gulf allies who feared that collapsing security in the impoverished nation was allowing an active al-Qaida franchise to step up operations.

President Ali Abdullah Saleh is the fourth leader to lose power in the wave of Arab Spring uprisings this year, following longtime dictators in Tunisia, Egypt and Libya.

But the deal ushering Saleh from power grants him immunity from prosecution and doesn’t explicitly ban him from the country’s political life — raising doubts that it will address Yemen’s many problems.

The deal opens the way to what will likely be a messy power struggle. Among those possibly vying for power are Saleh’s son and nephew, who command the country’s best-equipped military units; powerful tribal leaders; and the commander of a renegade battalion.

Saleh had stubbornly clung to power despite nearly 10 months of huge street protests in which hundreds of people were killed by his security forces. At one point, Saleh’s palace mosque was bombed and he was treated in Saudi Arabia for severe burns. When he finally signed the agreement to step down, he did so in the Saudi capital of Riyadh after most of his allies had abandoned him and joined the opposition.