Can the left thrive in Brazil’s Congress without the Workers’ Party?

The 2018 Brazilian presidential election was marked, among other things, by the sheer inability of political figures left of center to break with the hegemony of the Workers’ Party. Candidate Ciro Gomes got the closest to doing so, having negotiated coalition deals with pretty much any available party around, from the extreme left to the hard right. But former President Lula, from prison, commanded a strategy to isolate Mr. Gomes and keep the Workers’ Party (even with an understudy as candidate) as the sole major force in the left.

Things could change now, as at least three parties are set to form a leftist parliamentary front, without Lula’s political group. “The Workers’ Party doesn’t hold a monopoly over left-wing politics in Brazil. We don’t mean to isolate them, just differentiate our way of doing politics from theirs,” says Carlos Siqueira, chairman of the Brazilian Socialist Party (PSB), which stood with the Workers’ Party in most of the recent presidential races.

Together, the Democratic Labor Party (PDT), which presented Mr. Gomes as its presidential candidate, the PSB, which remained neutral in the race,...