Mexico's ruling party candidate has for the second time declared victory in the country's bitterly contested presidential election.
The election campaign has been intensely personal
"I won the election... it is irreversible," conservative Felipe Calderon told Mexican television.
Near complete results gave Mr Calderon a 1% lead over leftist candidate Andres Manuel Lopez Obrador.
But election officials have said they will not call a winner until after a recount beginning on Wednesday.
Both candidates have promised to respect the outcome of the poll, the closest in Mexico's history.
Supporters of both men celebrated late into the night, convinced of having sealed victory.
As the count put Mr Calderon marginally ahead on Monday, the National Action Party (Pan) candidate reiterated his claim.
"There is an irreversible result and it is in my favour," he told the Televisa network.
"The result gives me a very clear victory that cannot be reversed."
Mr Calderon's rival insisted on Sunday he too had won, but on Monday he sounded a more conciliatory note.
"If... it turns out the final result does not favour us, I am going to abide by the result," Mr Lopez Obrador told supporters at his Party of the Democratic Revolution (PRD) headquarters.
But he added he would "defend the will of the people if it favours us".
The outcome of the vote will be watched closely throughout the Americas but is of special concern to the US, where migration from Mexico is a key issue.
Officials say turnout was high, after a lengthy campaign marked by political insults and accompanied by a rise in drug violence.
Andres Manuel Lopez Obrador - Alliance for the Good of All (PRD)
Felipe Calderon - National Action Party (PAN)
Roberto Madrazo, Institutional Revolutionary Party (PRI)
Patricia Mercado - Social Democrat and Peasant Alternative Party
Roberto Campa - New Alliance
The leading candidates have been offering alternative visions of how to create jobs and boost the economy.
Among the 70 million people eligible to vote are thousands in the US, after a decision to allow Mexicans living abroad to vote for the first time.
In congressional elections, with 80% of polling stations reporting, the Pan was in line to win the most seats but to fall well short of gaining a majority in either house.
The Institutional Revolutionary Party (PRI), which ruled Mexico for 71 years, was set to fall into third place in Congress for the first time.
The BBC's Duncan Kennedy in Mexico City says the election has been portrayed as a fight between left and right, a choice between more state intervention or the continuation of free market policies.
Mr Lopez Obrador is a former mayor of Mexico City, who has championed the poor and promised major public building programmes.
Mr Calderon is a Harvard-educated former government minister who calls for more foreign investment and greater links to the global economy.
A third candidate, the PRI's Roberto Madrazo, is said to have been trailing in the polls.