possible motivation for the blockadeThe candidate that Los Mineros seems to be supporting is a guy named Napoleon Gomez Urrutia, and he is a Mexican exile living in Vancouver, of all places. He used to be head of Los Mineros until he was caught in a corruption scandal. I wonder if a campaign to bring this guy back to Mexico has anything to with this mess.
https://www.bloomberg.com/news/articles/2018-02-20/mexico-front-runner-stirs-firestorm-with-ex-fugitive-senate-pick
If you can believe it, Los Mineros has a Facebook page. And they endorse Gomez Urrutia on it:
https://www.facebook.com/Sindicato-Minero-Secc-271-764806500223143/