From what I hear the answer is no. The current opposition party (JxC) started supporting him when it was clear that their candidate couldn’t win against the incumbent party’s candidate (Sergio Massa, the current minister of economy), but they say they plan to vote against some of Milei’s more radical ideas.
What actually happens, and how many of his ideas Milei will actually try to get through parliament, remains to be seen.
I wonder if they are banking on, to put it into meme terms, “Heartbreaking: The Worst Person You Know Just Made A Great Point”.
And obviously I mean that in terms of a “great point” for the opposition.
I really don’t know anything about the parliamentary system of this country, hell I barely know enough about my own country, but this seems like at the best an interesting play and at the worst a huge miscalculation that will bite them in the arse.