Article published on the 2009-11-29 Latest update 2009-11-29 14:13 TU
Mujica, who spent 14 years in jail, took 48 per cent of the vote in the first round, just short of the absolute majority he needed, and now faces a second poll against the conservative ex-president Luis Lacalle who took about 28 per cent.
Opinion polls put Mujica ahead by around six to eight percentage points ahead but he is still viewed with suspicion by some of the country's conservatives because he was a founder of the Marxist Tupamaros guerilla movement.
He is a close ally of Venezuelan President Hugo Chavez, though he has said he styles himself more along the political lines of Brazil's populist President Luiz Inacio Lula da Silva.
"My model is Lula because he uses this model that makes permanent negotiation the centre of his policy," Mujica told Uruguay’s Busqueda weekly.
His running mate is former finance minister Danilo Astori, considered a political pragmatist, and the two are running on a platform that would maintain the economic policies of popular outgoing President Tabare Vazquez who is constitutionally prohibited from running for office again.
The 68-year-old Lacalle served as conservative president of Uruguay between 1990 and 1995.
Despite being a long way behind on the first vote, Lacalle could find backing from supporters of centre-right candidate Pedro Bordaberry, who was eliminated in the first round with 16 per cent of the vote.
Weather reports forecast thunderstorms for Sunday afternoon, but voters will face the biggest difficulties in the northeast where widespread floods have forced more than 6,000 people to evacuate their homes.