The leftist candidate for Mexico's presidency, Andres Manuel Lopez Obrador, has called on his supporters to occupy downtown Mexico City until a court orders a vote-by-vote recount of the July 2 election.

Lopez Obrador made the call Sunday to at least half a million supporters in the city's historic central plaza. He said he and the supporters should remain night and day until the votes are recounted and the country has a president-elect.

Lopez Obrador alleged vote fraud when the initial count showed he lost the election by less than one percent to conservative candidate Philipe Calderon.

Calderon has said the vote was fair and no recount was needed.

Mexico's top electoral court is hearing arguments from lawyers for both candidiates before declaring who will be Mexico's next president.

The court has until September 6 to issue its ruling.