Why has Brazil’s far-right failed to form its own party?

Over the last four years, Brazil’s President Jair Bolsonaro has time and again shown his ability to radicalize his electoral base. However, whenever he has attempted to take the next step in consolidating his political constituency — by forming his own party — he has come up against a brick wall. The so-called Alliance for Brazil, his planned far-right party, still lingers unregistered in Brazil’s Electoral Court due to a shortage of endorsing signatures. When it became clear that his plan had flopped, Mr. Bolsonaro joined the Liberal Party to run for reelection this year.

That the president is able to mobilize a substantial part of the electorate but is unable to institutionalize his ideology in the form of a political party is counterintuitive. This becomes even more puzzling as we approach October’s election, when Mr. Bolsonaro will make his case to remain in office for another...