Lopez Obrador says the election was "plagued with irregularities"
Some of Mexico's leading newspapers are in sharp disagreement over the measures being taken by leftist candidate Andres Manuel Lopez Obrador to challenge the official result of the presidential election.
Commentaries range from support for his right to demand a thorough recount to condemnation which accuses him of being a bad loser and putting the country's stability at risk.
El Universal believes that Mr Lopez Obrador is perfectly within his right in "letting the law speak" and demanding the recount.
"Mr Andres Manuel Lopez Obrador is acting within the law in challenging the result of the presidential election."
The editorial continues: "It is pretty worrying that there was an abstention level of over 40% and that the country has been split into three, meaning that, whatever the outcome, we will have a president elected by a minority of voters, albeit by a majority of votes cast."
"The next six-year government deserves to begin its term with full legitimacy so that it can tackle the country's unresolved problems swiftly and from a united front."
Writing in the same paper, economist Jorge Zepeada Patterson argues that the recount is justified as "Calderon was the candidate of the powers that be".
"It is vital to heed the suspicions and doubts of the losers, especially when they have already been victims in the past," he says, noting that Mr Lopez Obrador had lost a previous election for governor amid allegations of fraud.
The leftist Mexico City daily La Jornada launches a scathing attack on the electoral authorities, accusing them of using a variety of dubious tactics and calculations to arrive at a Calderon victory.
"The presumed errors of the electoral authorities are so monumental and inexplicable," La Jornada argues, that it is not surprising there is increasing talk of "fraud against the popular will".
La Jornada concludes that "sovereignty resides in the people and not in some doubtful calculations. If the ruling party is so sure of victory, it should accept a vote by vote recount."
For Reforma, "Lopez Obrador has every right to take his case to the authorities. What is not right is for him to exert pressure on them in order to advance his cause."
"He has already called a nationwide march, fresh demonstrations in the Federal District... and is announcing a second 'informative assembly'. Could it be that he wants to find in the streets what he failed to find at the ballot box?"
Writing in Reforma, Miguel Angel Granados Chapa asks the electoral judges "to dispel our doubts".
"The electoral judges hold in their hands the golden opportunity to mete out electoral justice at a crucial point for Mexicans."
Pablo Hiriart in La Cronica de Hoy takes Mr Lopez Obrador to task for mounting his challenge.
"Now Lopez Obrador wants to make us believe that he won the presidential elections. That the 800,000 members of the public who took part in the vote count on 2 July connived in a plot.
"That the IFE [Federal Electoral Institute] officials and the scientists who designed and monitored the Preliminary Electoral Results Programme (PREP) were also involved in the plot to strip him of victory.
"This is too much. At this point his supporters - people of good faith who voted for social change in the country - should give up in the face of the evidence: the leader's problems are incurable.
"Lie after lie, every day. Let's see if Felipe Calderon has the strength to withstand it. Let's hope so. The fate of the Republic is at stake," the columnist concludes.
BBC Monitoring selects and translates news from radio, television, press, news agencies and the internet from 150 countries in more than 70 languages. It is based in Caversham, UK, and has several bureaux abroad.