MEXICO CITY (Reuters) - The race to become Mexico's next president has closed slightly, but former Mexico City mayor and ruling party candidate Claudia Sheinbaum still has double the support of her main opposition rival, an opinion poll showed on Monday. Samuel Garcia, who is competing for the candidacy of another center-left party, Citizens Movement (MC), polled 8% support. A poll published in early October had given Sheinbaum 50% support versus 20% for Galvez, although that survey included a fourth, right-wing candidate who did not feature this time. "With the entry of Samuel Garcia as sole MC contender, the presidential ballot has been practically set in stone," Buendia & Marquez head Jorge Buendia wrote in El Universal. Separately, an analysis of several polls by research firm Consulta Mitofsky which stripped out undecided voters and those not backing any candidate showed Sheinbaum with 62.7% of effective support.

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Persons: Mexico's, Claudia Sheinbaum, pollster Buendia, Marquez, Xochitl Galvez, Galvez, Samuel Garcia, Sheinbaum, Andres Manuel Lopez Obrador, Buendia, Jorge Buendia, Garcia, Raul Cortes, Sarah Morland, Dave Graham, Andrea Ricci Organizations: MEXICO CITY, Mexico City, El Universal, Sheinbaum, Regeneration, Citizens Movement Locations: MEXICO, Mexico