Venezuela’s main opposition coalition agreed on Friday to unite behind former diplomat Edmundo Gonzalez as its challenger to President Nicolas Maduro in this summer’s election, acting one day before the deadline to formalise its candidate.

The decision was reached unanimously by the 10 parties in the Unitary Democratic Platform, Omar Barboza, the coalition’s executive secretary, said after a five-hour meeting that included discussions of other possible candidates.

The bloc had been allowed to provisionally register Mr Gonzalez on March 26 after the government came under a wave of criticism when opposition leaders said they were blocked from registering their candidate of choice.

Saturday was the deadline to make his candidacy final.

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Maria Corina Machado was banned from running for office (Ariana Cubillos/AP)

The opposition group needed to replace its first candidate, Maria Corina Machado, who easily won a primary organised by the bloc in October but was barred by the government from running after the ruling party-controlled State Comptroller’s Office disqualified her from holding public office for 15 years.

Mr Maduro’s administration has cracked down on the opposition before the July 28 presidential election despite promises to pave the way to fair elections in exchange for sanctions relief.

The Biden administration on Wednesday reimposed crushing oil sanctions, criticising Mr Maduro’s moves.

The governments of Colombia and Brazil also have expressed concern, and Guatemalan President Bernardo Arevalo accused Mr Maduro’s government of “consolidating an anti-democratic system”.

Venezuelan foreign minister Yvan Gil has called the criticism a “gross interference in matters that only concern Venezuelans”.

Mr Maduro, a self-proclaimed socialist leader, officially launched his candidacy last month for a third term that would last until 2031.

The election is likely to have more than 10 candidates, but except for the main opposition coalition, none are expected to pose a threat to Mr Maduro’s power base.