Rodolfo Torre Cantu was slain when gunmen opened fire on his two-vehicle caravan as it was heading toward the airport in Ciudad Victoria. He was en route to his final campaign appearance six days before local and regional elections in Mexico.
Tamaulipas state is on the border with Texas.
Torre Cantu's killing is the highest-profile political assassination in Mexico since the 1994 killing of presidential candidate Luis Donaldo Colosio, the Associated Press reported.
-- Lance Murray