While Venezuela is expected to get a majority in secret balloting in the 192-nation U.N. General Assembly, Caracas may not achieve the required two-thirds vote, leaving open the possibility of a compromise candidate.
"This is a real wrestling match. This is a heavy-weight encounter," said Larry Birns, director of the Washington-based Council on Hemispheric Affairs.
"If they vote with their head they're voting against Venezuela because, the United States is certainly going to make this an anti-Venezuela position," he said.
"If they vote with their heart they are basically saying: 'we're tried of being pushing around by Washington and we're just going to go our own way on this,"' Birns said.
Venezuela's President Hugo Chavez, up for reelection in December, has campaigned hard for the seat in 2007-2008, sending assistance to Latin American countries as well as contributing to food aid in Africa.