I'm not so sure, imagine if Argentina pretended to elect a "communist" that then seized some American assets in the country and planned to hand them to the Chinese?

The tricky bit is making sure the resulting US occupation becomes long lasting, I think you would have to store away substantial amounts of money to bribe a gaggle of senators for a few decades to make incorporation possible.

Argentina is mostly white, Christian and doesn't have any part in the internecine blood feuds that roil South Asia or the middle east. Lots of land, and well educated. No history of slavery (well at least not like its neighbor Brazil). So, yeah, it'd be a great addition to the USA. I'd take it.