MEXICO Metropolis, Feb 7 – Mining-targeted conglomerate Grupo Mexico (GMEXICOB.MX) is shifting closer to getting Citigroup Inc’s (C.N) Mexican shopper banking unit but faces an uphill route in promoting the offer to skeptical buyers. Grupo Mexico, headed by billionaire German Larrea, is amid the very last candidates continue to standing in Citi’s calendar year-extended journey to sell its retail unit, known as Banamex, and has positioned a bid of up to $8 billion for it, Reuters described earlier this month. But some analysts, shareholders and even Grupo Mexico executives have however to be convinced of the deal’s industrial logic. A Grupo Mexico executive, who spoke on situation of anonymity, explained…