Venezuela and Guatemala face a U.N. General Assembly vote Monday for a non-permanent seat on the prestigious Security Council.
The two nations are competing for the Latin American seat being vacated by Argentina. Some U.N. officials say it is the most tightly-contested Council race for a non-permanent seat since the Cold War.
Venezuelan President Hugo Chavez, a sharp critic of the Bush administration, has traveled to numerous countries to rally support for his bid for the rotating two-year seat.
The United States has put its support behind Guatemala.
Western diplomats have expressed concern that Venezuela will use a seat on the Security Council to challenge the United States in the world body.
If neither Venezuela nor Guatemala is able to muster a two-thirds majority, Latin American nations could decide to nominate another candidate.
The Security Council has 15 seats, including five permanent members with veto power - the United States, Russia, China, Britain and France. The 10 non-permanent seats are filled by the U.N.'s regional groups for two-year terms.