Paraguayans are voting Sunday in presidential and congressional elections that is a strong test to the Colorado Party, the world's longest-ruling political party.
Early polls show ex-bishop Fernando Lugo edging out the ruling party's Blanca Ovelar and retired army general Lino Oviedo. However, analysts say the race is too close to call.
Experts also claim Lugo is posing the toughest challenge to the ruling party in its uninterrupted 61-year reign.
Lugo is heading a center-left coalition but has steered clear of South America's radical leftist leaders, such as Venezuela's Hugo Chavez.
Dozens of international observers are watching for signs of electoral fraud in the South American country known for widespread corruption.