¡Qué alguien me explique! Why did AMLO senators vote against the tobacco tax?

Yeidckol Polevnsky, Rosalinda López, Josefina Cota Cota and Francisco Castellón Fonseca are four of the PRD senators who on numerous occasions have professed their loyalty to Andrés Manuel López Obrador, and among a group of PRD and PT senators who most recently declared they would back AMLO as a presidential candidate.

Two days ago, however, when the Senate ratified the proposed rise in 7 pesos - a mere 50 U.S. cents - increase in tobacco taxes per cigarette pack, the four legislators voted against it - the only ones from the PRD to do so.  In addition, three Convergencia senators, a party that also has declared its ultraloyalty to AMLO, did the same - Ericel Gómez Nucamendi, Francisco García Lizardi and Eugenio Govea Arcos.
From the Partido del Trabajo, ostensibly diehard andresmanuelistas, its senate coordinator Ricardo Monreal abstained from voting, while his PT colleague Javier Obregón Espinoza voted in favor.

Why? Why on earth would these ostensibly "radical" politicians vote against raising the tobacco tax?
¡Qué alguien me explique!

a) Is it that AMLO is particularly pro-smoking?
b) Can it be that these "radical" senators are really corrupt opportunists, bought and paid for by the tobacco industry?
c) ????

You make your pick.