Andrés Oppenheimer writes what is blaringly obvious about U.S. policy toward Latin America, especially with regard to Venezuela:
Trouble is, most Latin American countries are reluctant to cast a vote alongside the Trump administration as long as the U.S. president continues with what they see as his insane Mexico bashing.
Trump's anti-immigration, anti-trade, anti-Mexican tirades — as when he said that Mexico is sending mostly criminals, rapists and "bad hombres" to the United States — have made him so unpopular in Latin America that he has become politically radioactive. No Latin American president wants to cast a vote against Venezuela and risk to be painted at home as a Trump puppet.
This is what I've been getting at with my arguments about "leverage." Opening up to Cuba increased U.S. leverage and also opened space for Latin American countries not to feel the knee-jerk reaction to oppose U.S. policy. This doesn't mean any guaranteed results--indeed, it's not easy to get a majority in the OAS. But otherwise the door is guaranteed to be slammed shut. Dumb policy toward one country makes some goals impossible to achieve.