This is something I have little knowledge about but of course I have my opinion. The way I understand what I've read the president wanted to pass a constitutional amendment so he could serve more than a 4 year term. Many opposed this even people in his own party. I think this guy was trying to do what Chavez did and become a leftist dictator. I think the preemptive ousting was to prevent a tainted vote on the amendment.
I think many South American Countries are feeling pressure from such leftists as Mr Chavez, Bolivian President Evo Morales and former Cuban leader Fidel Castro. And they use the mantra that some floorters use; that the USA is not a friendly nation and doesn't care about Latinos.