Libya’s prime minister-elect failed a confidence vote by an overwhelming margin on Sunday, removing him from office and throwing the country into yet more political uncertainty as time ticks on an investigation into attacks that killed four Americans last month.

The decision by Libya’s legislature means that the government may remain without permanent, democratically-elected leadership for many weeks. But without a government in place, the investigation into the attacks that killed U.S. Ambassador J. Christopher Stevens and three other Americans may be a low priority for Libyans. The extent to which the U.S. part of the investigation can operate freely in Libya also may be hampered by the domestic political chaos.

Some Libyan officials have raised sovereignty concerns about extensive FBI operations in Benghazi, the eastern coastal city where the Americans were killed at two U.S. government outposts. Safety concerns also have kept the FBI away from the city, although it visited Thursday for an extensive sweep of the U.S. mission there.

Prime Minister-elect Mustafa Abushagur lost Sunday’s confidence vote with 125 members of the 200-member Libyan General National Congress voting against him, 44 in favor and the remainder abstentions or no-shows. Abushagur had come under heavy fire last week for proposing a cabinet that critics said was filled with political unknowns. Following the protests he came up with a new slate but lost the vote.

Now Libya’s legislature must select a new prime minister who will have to assemble another cabinet. The process could take weeks. Abushagur, a longtime engineering professor in the United States, became Libya’s first democratically-chosen prime minister since Sept. 12, a day after the attacks in Benghazi.

“Your terms contradict my values and terms for forming my cabinet,” Abushagur told the legislature ahead of the vote. “I’m not going to submit to your conditions.”

The FBI has a team of investigators who have been sitting in Tripoli for weeks but have had limited success in doing work in Benghazi, hundreds of miles away. Many witnesses to the attack say they have not been contacted by Libyan or American investigators. Last week, Libyan deputy foreign minister Mohammed Abdel Aziz said that approval had been slow in coming for the Americans to fly to Benghazi and operate freely there.

With the delay, the interim government in place since last year will continue to run the country.