Brazil

Brazil is a unitary republic with a presidential form of government. In the Economist Democracy Index 2024, it received an overall score of 6.49/10 ("flawed democracy") and a rating of 9.58/10 for electoral processes and pluralism.

At the federal level, both houses of the bicameral legislature, the House of Representatives and the Senate are elected directly in constituencies corresponding to the 27 states. All 513 seats of the House of Representatives are elected in all states every 4 years. In the case of the Senate, each of the 27 states gets 3 senators, making a total of 81 members. Senators are elected for 8-year terms, with two and one elected in each state every four years (with a 4-year shift, elections are held for 54 and 27 seats, respectively, every 8 years).

The minimum age for active suffrage (the right to vote) is 16 years, and voting is generally compulsory for those over 18 and under 70.

President

Presidential elections are held every 4 years at the same time as the legislative election, in a classic two-round electoral system. The first round is held via a single-choice vote and the two candidates with the most votes advance to the second round if no one receives a majority (more than half of the valid votes, 50%+) in the first round.

Congress

House of Representatives

In the case of the House of Representatives, a completely open list, regionally proportional representation system is used. The D’Hondt method is used to distribute the seats between the parties. The 2% legal threshold is not nationwide, but per constituency, so it is not significant in most districts, and may play a role in the 2-3 most populous districts. The seats are not distributed proportionally between the states, as each state is entitled to a minimum of 8 representatives, and a maximum of 70. This favors the smallest states, the rule affects São Paulo the most negatively, which has only 70 representatives instead of 110. Other states are not affected by the upper limit, but the allocation within the limits is not completely proportional either.

Because of the open list voting, voters can vote for a candidate within the list of their choice (these are also called preferential votes). In Brazil, the principle of fully open lists applies, and the order of the list is entirely determined by the voters who voted for that list. Parties can field a joint list, but even then only the number of votes of the candidates within the list counts.

Senate

The electoral system for members of the Senate depends on the year in which the election takes place. When one-third of the members are up for election, the election is done in quasi single-member districts via single-round, choose-one plurality rule, first-preference plurality (FPP) aka first-past-the-post (FPTP). When two-thirds of the body is elected, the two senators in each state are elected at once, using a single-round, double choice, plurality block voting for two seats. Thus, the election is essentially "winner-take-all" in both cases.

Notes

This is the description of the electoral system of Brazil as of 01.08.2026 on Electoral Knowledgebase. Sources and further information on this topic:

Election Passport - Brazil

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