Somali leaders have overwhelmingly approved a new constitution that sets the stage for a more powerful and representative government.

Ninety-six percent of a special constituent assembly voted in favor of the measure Wednesday, ahead of a U.N. deadline for completing a government transition.

Last week, the U.N. Security Council said Somalia's political transition was at a “decisive phase” and needs to be completed by August 20. Somalia must still select a new parliament and elect a new president.

Shortly before Wednesday's vote, security officers killed two suicide bombers who tried to attack the assembly's venue in Mogadishu. Authorities say at least one bomber detonated explosives, injuring several security officers.

No group immediately claimed responsibility for the attack, but Somalia has long battled al-Qaida-linked al-Shabab militants.

Somalia's Transitional Federal Government has been in place since 2004. It has been unable to assert power because of chronic infighting and conflict across the country.