Andrés Manuel López Obrador, the leftwing candidate in Mexico’s presidential elections, refused on Thursday night to accept defeat at the hands of his centre-right rival, Felipe Calderón.
He called instead on his supporters to gather for a mass rally in the capital on Saturday.
“It is clear that there was manipulation [of the counting],” Mr López Obrador, of the Democratic Revolution party (PRD), said, hours after Mr Calderón had taken a wafer-thin lead.
“We are not going to sit back with our arms crossed.”
With 99.9 per cent of the vote counted last night, Mr Calderón, of the ruling National Action party, had won 35.86 per cent, compared with Mr López Obrador’s 35.32 per cent.
Mr López Obrador’s call for a rally in Mexico City’s Zócalo Square, which can hold more than 100,000 people, is a new phase of his party’s protest over the counting of the vote.
While the former mayor of Mexico City was careful in his choice of language and said that the party would “act responsibly”, his call will heighten fears that the rally could spark street protests and possibly outbreaks of violence.
Late Wednesday, a top PRD official told the Financial Times that a “very strong” civic movement was already mobilising, and that Mr López Obrador had no choice but to take the lead to maintain calm.
“If Andrés Manuel does not assume leadership of it there will be chaos,” said Manuel Camacho, who is one of Mr López Obrador’s key strategists. “The people are very angry.”
In the early hours of Thursday, a beaming Mr Calderón appeared before a rowdy group of supporters at his party’s headquarters in Mexico City and called for national unity in an address that fell just short of claiming victory.
“To those who voted for me I thank you because your votes ensure that there is democracy in Mexico; to those who did not vote for me I ask that you give me the opportunity to win your confidence,” he said.
Mr Calderón’s small lead sparked significant gains for Mexican bonds and shares on Thursday, and the currency strengthened by 1.5 per cent during mid-morning trading.
But Mr López Obrador described Mr Calderón’s speech as “a provocation”, and insisted: “We are going to prove that he didn’t win. Nobody can declare himself president of the Republic without moral authority”.
Mr López Obrador’s party claims that both the unofficial and official counts were full of “inconsistencies”.
The party is claiming that at least 40,000 ballot boxes in last Sunday’s election – about a third of the total – were subject to some kind of “irregularity”.
It has demanded that the country’s Federal Electoral Institute either authorises a full manual recount, which would involve opening every one of the roughly 130,000 ballot boxes, or that it annuls the election.
On Thursday, Mr López Obrador said he would take a legal case to the Federal Electoral Tribunal, the country’s highest electoral court. “We won and that is what we are going to demonstrate in the tribunal,” he said.
According to Mexico’s electoral laws, parties have four days from the end of the official count to raise objections and lodge complaints. The tribunal will then have until the end of August to make a ruling, which is final.