(Adds Tillerson landing, details on Austin speech)
By Gabriel Stargardter
MEXICO CITY, Feb 1 (Reuters) - The United States' top diplomat landed in Mexico on Thursday with debate swirling over the government's efforts to win favor with Washington and save the NAFTA pact from collapse, sparking concerns it is ceding sovereignty to its northern neighbor.
Mexico has been at pains to prove itself a good ally to the United States on combating drug trafficking and immigration, in hopes this would help efforts to renegotiate the North American Free Trade Agreement on as favorable terms as possible.
Those secret efforts sprang into view this week, when Reuters exclusively reported that Mexico is considering allowing U.S. air marshals aboard commercial cross-border flights, igniting a debate over what lengths Mexico should go to in order to win favor with its top trade partner.
"The question is, what else is (Foreign Minister Luis) Videgaray giving to Trump and his collaborators in exchange for preserving NAFTA?" Salvador Garcia Soto asked in his El Universal newspaper column, decrying Videgaray's "opaque" maneuvering.
U.S. Secretary of State Rex Tillerson landed in Mexico City on Thursday afternoon and was due to have dinner with Videgaray and other senior Mexican government and national security officials at U.S. Ambassador Roberta Jacobson's residence.
Although Tillerson has not been a prominent player in the NAFTA discussions, the future of the treaty is certain to loom over his visit, especially at a trilateral meeting with Canada's Foreign Minister Chrystia Freeland on Friday.
Mexico's government, and particularly the foreign ministry, has pushed hard to defend NAFTA, a lynchpin of its export-led economy, ahead of a July 2018 election in which the ruling Institutional Revolutionary Party is currently polling third.
"All our efforts right now are based around NAFTA and making sure the pact doesn't collapse," said a senior Mexican diplomat.
Videgaray has said closer cooperation with the United States is the best way to achieve Mexico's foreign policy aims.
"Obviously that would be something that we strongly want to avoid," Videgaray said at an event in New York late last year, reffering to NAFTA collapsing. "We realize that we could achieve much more by being constructive and by approaching the relationship looking for common ground ... with very active cooperation."
Quizzed by ruling party lawmakers on Tuesday, Videgaray denied the air marshals were part of any NAFTA quid pro quo, but said the government was studying the plan.