Election changes should reduce fragmentation. And benefit the ‘Big Center’

The filling of seats for Brazil’s House follows a one-of-a-kind system (for which we gave an overview back in 2018). This year, the rules will get a bit more complicated — and the changes could radically alter the landscape of the Brazilian Congress.

To understand how the new rules apply, it is necessary to first get the nuts and bolts of the current system. Here’s what you need to know:

After ditching spoiled votes and adding up all the votes for a party, authorities calculate the so-called electoral thresholds by dividing the number of valid votes by the number of seats in dispute. 

In theory, if a party obtains 10 percent of the votes in a given state, it will take 10 percent of that state’s House seats. But things usually get a tad more complicated.

The first round of seat attribution always leaves some seats unfilled as the numbers obtained by dividing votes by seats are never round. For example, a party can get 73,000 votes in a state where the threshold for a seat is 70,000 — with 3,000 “leftover” votes. As the same happens with all parties, some seats remain empty.

At this point, a more complicated formula is applied, distributing the leftover votes to the parties with the best voting averages, as political scientist Jairo Nicolau explained in a 2017 book.

In 2022 and beyond, the leftovers will only be distributed among candidates who have on their own met at least 20 percent of their state’s threshold and whose party obtained a minimum of 80 percent of it. Had these rules been in force in 2018, only 259 of the current 513 congresspeople would have qualified for a House seat.

The move would also dramatically reduce the number of parties with representation, from the 30 elected...