The U.S. ambassador to Liberia says she believes the country's election officials will be able to hold a free and fair vote in polls scheduled for next week.

Linda Thomas-Greenfield told VOA she is confident Liberians will choose voting over violence.

But the envoy said the U.S. is concerned about possible unrest. She urged political party leaders to discourage their supporters from engaging in political violence.

The elections are scheduled for October 11. However, Liberia's Supreme Court has yet to rule on whether the top candidates, including President Ellen Johnson Sirleaf, have met a constitutional requirement.

Liberia's constitution says candidates must be a resident in the country for 10 years prior to a vote. Many politicians left Liberia during 14 years of civil war and unrest that ended in 2003.

An opposition party, Liberia's Movement for Progressive Change, has asked the Supreme Court to rule ineligible six of the 16 candidates, including President Sirleaf and her main challenger, Winston Tubman.

President Sirleaf was elected president in the country's first post-war polls in 2005.

If no candidate wins more than half the vote in the October 11 elections, a second-round runoff will take place in November.

Thomas-Greenfield said the U.S. is providing financial aid for an election observer team from the U.S.-based Carter Center, and is consulting with African officials to ensure oversight of Liberia's poll.