Please, stop comparing peronismo with republicans cause is exactly the opposite. The republicans, as far as I know, are the right in the US. Conservative, for free market, against taxes, against things like gay marriage, or other progressive measures, etc. Conservative, theres something to conserve (social order with its powers, etc)
Peronism in Argentina are pro-working class governments. There is right wing peronism as Menem, but that was really not peronism. In fact, they violated the three slogans the peronism historically had: politic sovereignty, economic independence, and social justice. The real peronismo was in fact the historic one, not the one of the 90s, the proof is that in his campaign Menem used all his features, all its "flags", proposing populism, like "revolución productiva" and "salariazo", google it, and did the exact oposite.
So Peronism if not left, can be catalogued as centre left, as working class governments, as keynesianism, as nac & pop, etc. The historical enemy of peronism is the oligarchy, (you can study this, again, google is your friend) people, that particular political subject that in the US is very well represented by republicans.