Colombian President Juan Manuel Santos asked electoral authorities Wednesday to investigate accusations that his 2014 re-election campaign took a bribe from scandal-plagued Brazilian construction firm Odebrecht.
Santos, the 2016 Nobel Peace Prize winner, is seeking to clear his name after a former senator leveled the damaging accusation, which the government vehemently denies.
"I request the CNE (National Electoral Council) open a wide-ranging investigation as soon as possible so the full truth of the Odebrecht case comes to light," Santos wrote on Twitter.
Colombia's attorney general, Nestor Humberto Martinez, said Tuesday that prosecutors have opened an investigation into allegations the Santos campaign took a $1 million bribe from Odebrecht.
The case is the latest spillover from a giant scandal in Brazil involving the state oil company there, Petrobras, which was bilked for billions of dollars over the course of a decade by corrupt executives, politicians and contractors -- including Odebrecht.
Since the Brazilian scandal broke, Odebrecht's dirty dealings around Latin America have been coming to light.
The public officials allegedly bribed by the construction giant include Colombian ex-lawmaker Otto Bula, the source of the accusations against the Santos campaign.
Bula was allegedly hired by Odebrecht to help the construction company win a 500-kilometer (300-mile) road project in Colombia.
Martinez said Bula paid a bribe to Santos's campaign manager via an intermediary.
Bula is close to former president Alvaro Uribe, Santos's fiercest critic.
Santos's transparency secretary, Camilo Enciso, has roundly rejected the accusations, calling Bula a "shady character" and accusing Uribe's camp of "attacking with lies."
The attorney general acknowledged Wednesday that investigators have no physical evidence against the Santos campaign.
He said the probe was based on Bula's testimony, which "makes no link to the president" himself.
The controversy comes as the Santos government implements a historic peace deal with Colombia's FARC guerrillas and seeks to negotiate another with a rival rebel group, the ELN.
A corruption investigation could damage Santos as he races to end a half-century conflict that has killed more than 260,000 people and left 60,000 missing.
The twin Petrobras and Odebrecht scandals have sent shockwaves around Brazil and Latin America, leading to the arrest of a laundry list of top politicians and executives and freezing numerous mega-projects awarded to Odebrecht.