Mexico's Sheinbaum grows lead in presidency race ahead of decision-poll

FILE PHOTO: Former Mexico City Mayor Claudia Sheinbaum greets supporters during an event in Mexico City

MEXICO CITY (Reuters) - Former Mexico City Mayor Claudia Sheinbaum has increased her lead in the race to be ruling party candidate in next June's presidential election with just days to go before the winner is chosen, an opinion poll showed on Monday.

The Aug. 18-23 survey of 1,000 adults by newspaper Reforma showed support for the 61-year-old Sheinbaum to represent the ruling leftist National Regeneration Movement (MORENA) rising to 37% from 31% in a previous poll from May.

Backing for her closest rival in the MORENA contest, ex-Foreign Minister Marcelo Ebrard, slipped to 22% from 26% over the period, according to the poll, which had a margin of error of plus or minus 4 percentage points.

MORENA will conduct national polling this week to select a winner to be announced on Sept. 6.

Among those competing for the presidential candidacy of an opposition alliance, the poll showed that Senator Xochitl Galvez performed best against MORENA's leading contenders, closely followed by Senator Beatriz Paredes.

The opposition alliance - the center-right National Action Party (PAN), the centrist Institutional Revolutionary Party (PRI) and center-left Party of the Democratic Revolution (PRD) -is due to announce their presidential candidate on Sunday.

Galvez, a feisty, unconventional politician who has lifted the spirits of a struggling opposition, represents the PAN in the Senate. Paredes is a veteran operator and former chair of the PRI, which dominated Mexico in the 20th Century.

Opinion polls show MORENA is by a wide margin the most popular party, bolstered by the robust approval ratings of President Andres Manuel Lopez Obrador, who cannot run again. By law, Mexican presidents can only serve a single six-year term.

The opposition's chances are complicated by the fact that a fourth party, the center-left Citizen's Movement (MC), has yet to decide whether it will join the others, or run separately.

In a three-way match-up, Sheinbaum was seen winning 44% of the vote, Galvez, 27% and Samuel Garcia, MC governor of Nuevo Leon state, 12%, the Reforma poll showed. With Paredes as candidate, she garnered 25%, Sheinbaum 46% and Garcia 11%.

Ebrard was also seen winning comfortably against both women, albeit by slightly smaller margins.

(Reporting by Dave Graham; Editing by Marguerita Choy)