MEXICO CITY, June 6 (Reuters) - The head of Mexico's leftist National Regeneration Movement (MORENA) party, Andres Manuel Lopez Obrador, called on Tuesday for a recount, "vote by vote" of Sunday's key State of Mexico gubernatorial election.

With nearly 98 percent of returns in from polling booths, the candidate for President Enrique Pena Nieto's Institutional Revolutionary Party (PRI) had 34 percent of the vote compared with 31 percent for MORENA's candidate.

"As of today we have asked the electoral institute of the State of Mexico carry out a recount of votes. We want all votes to be counted, vote by vote, voting station by voting station," said Lopez Obrador. (Reporting by Dave Graham; Writing by Anthony Esposito; Editing by Leslie Adler)