Mexico's highest electoral court has dismissed a legal challenge to the result of July's presidential election by the second-placed left-wing candidate, Andres Manuel Lopez Obrador.
Mr Lopez Obrador had accused winner Enrique Pena Nieto of using illicit money to buy votes and media coverage.
But the court ruled that he had not produced enough evidence of wrongdoing.
According to the official count, Mr Pena Nieto won 38% of the vote to Mr Lopez Obrador's 31%.
All seven judges on the Federal Electoral Tribunal voted on Thursday to reject the runner-up's accusations.
Mr Pena Nieto's Institutional Revolutionary Party (PRI) had denied any wrongdoing.
The BBC's Will Grant, in Mexico says that is now clear that Mr Pena Nieto will be sworn in as Mexico's next president on 1 December.
There were minor scuffles between police and anti-PRI protesters outside the court after the decision was announced.
The dispute has prompted street demonstrations in support of Mr Lopez Obrador's challenge, and further large protests may take place in Mexico City in the next few days, our correspondent says.
But there are very options left for Mr Lopez Obrador and his supporters, and the tribunal's decision - while expected by many - may have taken the wind out of their sails, he adds.
Mr Lopez Obrador, a former mayor of Mexico City who leads the Party of the Democratic Revolution (PRD), accused the PRI of bribing voters with presents ranging from supermarket gift cards to fertilizer, cement and livestock.
He also claimed Mr Pena Nieto had broken campaign rules by overspending, and that Mexico's media was biased in favour of the PRI candidate.
The PRI dismissed the allegation as "defamation".