Aug. 18 (UPI) -- Bolivia is headed to a presidential run-off election between a center-right politician and a right-wing candidate after voters on Sunday rejected another term of the Movement for Socialism, which has governed the country for nearly two decades. According to preliminary results from the South America nation's election commission, Sen. Rodrigo Paz Pereira, 57, of the Christian Democratic Party, had 1.6 million votes for 32.1% of the vote share, followed by former rightwing