Mexico presidency frontrunner Sheinbaum slightly widens lead, poll shows

Presidential candidates attend the last presidential debate at the Tlatelolco University Cultural Center, in Mexico City

MEXICO CITY (Reuters) - Mexican ruling party candidate Claudia Sheinbaum slightly extended her large lead over her main rival in the contest for the presidency on June 2, an opinion poll showed on Wednesday.

The May 22-27 survey by polling firm Parametria showed Sheinbaum, from the National Regeneration Movement (MORENA) with 50% support, ahead of Xochitl Galvez, the candidate for an opposition alliance of three parties, with 34%.

A prior April survey by the firm showed Sheinbaum, Mexico City's former mayor, at 44% support, and businesswoman-turned-politician Galvez at 31%.

The poll gave a third contender, Jorge Alvarez Maynez of the opposition center-left Citizens' Movement (MC), backing of 13%, an increase of five points over April.

The face-to-face poll of 1,000 people had a 3.1% margin of error.

The vast majority of Mexican polls have pointed to Sheinbaum winning comfortably in Sunday's election.

Sheinbaum, a 61-year-old scientist who has been a close ally of the current President Andres Manuel Lopez Obrador for decades, could become the first woman to rule the country.

(Writing by Drazen Jorgic; Editing by Marguerita Choy)