There is none, the only opposition is the kirchnerismo that is facing a power vacuum after the leader, Cristina Kirchner, was forbidden to participate in further elections due to corruption. Her son and the governor of the biggest province are duking it out with no end in sight.

Not a defense of libertarians but in general most of the old guard libertarians don’t like Milei in Argentina due to his support of some polices that have the state still doing stuff. All from trying to crack down on legal weed to increasing the subsidies on poor children.