According to Wikileaks cable 06VATICAN61, Sandoval met with U.S. ambassador to the Vatican, Francis Rooney, in 2006, and asked the U.S. for help in stopping the presidential ambitions of Andrés Manuel López Obrador, who narrowly lost that year's election.
Given Mexican law, this type of political proselytizing is not allowed by the church.
The archdiocese of Guadalajara admitted that a meeting took place, but denies that the cardinal even mentioned AMLO. Perhaps the U.S. embassy personnel are simply making the entire thing up?
As the Brits are fond of saying: Not bloody likely.
(Here is a direct link to the cable, for your reading pleasure - "He asked whether President Bush could help")
Strangely, AMLO seems to think so - his response to the apparent revelation was very muted, saying only that it he doubted it. Is he still, like in 2006, holding out for good relations with the church? Given that Sandoval already in 2006 appeared to see him as a "danger," this seems a lost cause.