Early exit polls late Sunday showed that Bolivia's presidential race will likely go into a second round, with the ruling leftist party headed to its worst electoral defeat in a generation.

Dark horse centrist senator Rodrigo Paz was the surprise leader with over 32% of the vote, according to projections based on partial results by Ipsos and Captura polling firms.

Jorge "Tuto" Quiroga, a right-wing former president who briefly led the country in 2001, was second with around 26%.

Business tycoon Samuel Doria Medina was projected to be in first place in pre-election polls, but he was relegated to third.

Meanwhile, the ruling Movement for Socialism, or MAS, party is on track to lose power after nearly 20 years of dominance.

Bolivia headed for unprecedented presidential runoff 

Observers did not expect any candidate to reach the necessary majority in the first round.

To avoid a runoff, presidential candidates need to win more than 50% of the vote or over 40% support with a 10 percentage point lead.

The second round, scheduled on October 19, will be unprecedented in the country's history.

Bolivia's general election on Sunday has been overshadowed by the worst economic crisis in four decades and the absence of former leftist President Evo Morales.

Bolivia's possible political shift

Sunday's vote could end the Andean nation's long-dominant leftist rule. For the past two decades, Bolivian politics has been defined by the ruling MAS party.

Bolivia's constitutional court has barred its founder, Morales, who first came to power in 2006, from running in this race. The court ruled that he had already exceeded the two-term limit.

The outgoing socialist President, Luis Arce, who had fallen out with Morales, opted not to seek re-election due to his plummeting popularity.

Instead, Arce nominated a senior minister, Eduardo del Castillo, to be an MAS candidate. Projections late Sunday show that he had just over 3% of the vote.

Morales, who served three consecutive terms, urged his supporters to cast a blank vote in protest over his disqualification.

The ex-leader has been holed up in his political stronghold in Bolivia's tropical region of Chapare for months as he evades an arrest warrant on charges related to his sexual relationship with a 15-year-old girl while in office.

Edited by: Dmytro Hubenko