Bolivia's interim President Jeanine Áñez has stop the primary election due on 18 October.
She stated she didn’t wish to cut up the vote and see the return to workplace of former President Evo Morales' Mas socialist get together.
Mas candidate Luis Arce is main in opinion polls, with Ms Áñez trailing in fourth place.
Ms Áñez was sworn in final yr after Mr Morales resigned and left the nation amid allegations of electoral fraud.
Mr Morales, who at present lives in Argentina, later stated he was pressured into exile by the police and the army.
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Mr Morales served as Bolivia's president for nearly 14 years, from 2006 to 2019, after profitable three successive elections.
How did Jeanine Áñez clarify her choice?
In a video message, Ms Áñez stated: "Today I put aside my candidacy for the presidency of Bolivia, for the translates of democracy."
She stated she determined to drop out due to "the risk that the vote is divided among several candidates and that as a result of that division, the Mas would end up wining".
"If we don't unite, Morales will return. If we don't unite, democracy loses," Ms Áñez added, with out saying which candidate she would now be backing.
A ballot printed earlier this week recommended that Luis Arce might win the election within the first spherical.
Ms Áñez's management has been controversial from the beginning, the BBC's South America correspondent Katy Watson reviews.
Mr Morales' supporters say she assumed the presidency after he was ousted in a army coup – and he’s the rightful leader.