Brazil votes on Sunday 4 October, and on WhatsApp one party is well ahead. The Partido dos Trabalhadores, Lula's PT, has 36,413 followers on its official channel. The Partido Liberal, Jair Bolsonaro's party, has 19,693. PT is close to double.
This is the country where WhatsApp became a political weapon. In 2018 a lot of the Bolsonaro campaign ran through groups and mass forwards, and we have written about how that machine worked. Eight years later the picture on the official channels is the other way round: the left has the bigger audience, and it is the one filling it with content.
We track the official WhatsApp channels of political parties and read their public follower counts on a schedule. The follower figures here are from 28 September 2026, and every reading is in the open dataset. The posting and engagement figures further down are not. They come from us following both channels through the campaign, and we say below exactly how rough they are.
The ranking
We have 30 Brazilian parties in the registry. Only six run a national WhatsApp channel we could find.
Three channels count and three barely register. After PT and PL comes Missão, less than 2,000 followers behind PL. Then there is a cliff: PDT, União Brasil and PSDB are all under a thousand.
The more surprising list is the one that isn't on the chart. MDB, PSD, PP, Republicanos, PSOL and PSB, parties with big benches in Congress, have no official channel we could find. In a country where WhatsApp is this political, most of the party system still hasn't opened one.
The campaign surge
PT's channel was not always this far ahead. In September 2025 it had around 11,000 followers. By 15 August 2026, the day before the official campaign period opened, it was at about 21,000. Six weeks later it is at 36,413.
That is roughly 15,000 new followers in six weeks, a 73% rise, and more than PT gained in the entire previous year. The campaign did that. Whatever the party is doing on its channel right now, people are signing up for it.
We know less about how PL got to 19,693. Our history for its channel is thin: the Internet Archive has it at about 3,100 in June 2024, and our next reading is today's. It grew a lot over two years, but we can't tell you when, so we won't pretend to.
What each channel sends
Follower counts only show who signed up. What decides whether a channel matters is what lands in those people's WhatsApp every day, so we followed both channels through September.
PT's channel is busy. These days it sends around five posts a day, and a lot of it is video, plus images and short cards. The posts carry political messages and concrete proposals, and a good share of them feature influencers and creators rather than just party officials. That is a choice. A post fronted by a creator looks like the rest of what people get on their phones, not like a press release. The posts typically collect around 200 reactions each, and the most shared ones reach about 400 forwards.
PL's channel works differently. It posts about twice a week. Most of what it sends is criticism of PT: attacks on the government and on Lula rather than its own programme. Posts get about 110 reactions on average, and that has been falling during the campaign, down to around 90. Forwards hold up better, at about 200 per post.
That last number deserves a second look. Relative to its size, PL's audience forwards a lot. A post that attacks the other side is something people pass on to a family group, even when they don't bother to react to it. Forwarding was the engine of the Bolsonarista WhatsApp in 2018, and the habit looks like it's still there.
Doing the rough maths
Per follower, the two channels are not that far apart. Around 200 reactions on 36,000 followers and around 90 on 20,000 are both in the region of five reactions per thousand followers. PL's audience isn't dead, and PT's isn't unusually devoted.
The gap is volume. At about 35 posts a week and around 200 reactions each, PT's channel gathers something like 7,000 reactions a week. PL, at two posts and 90 reactions, gets something like 180. These are back-of-the-envelope numbers built on rough averages, but even if we're off by half, PT is producing dozens of times more activity on WhatsApp than its main rival in the final stretch before the vote.
PL's falling reactions during a campaign are the odd detail. Election season should be when a party's base is most fired up. It could be fatigue with a channel that mostly says the same thing about the other side, or it could mean the party's energy on WhatsApp is going somewhere other than its official channel, like groups and candidates' own numbers. We can't see those from outside, so we are not going to guess which.
The one catching up: Missão
The third channel is the one to watch. Missão, the party founded by the Movimento Brasil Livre (MBL), has 17,796 followers, less than 1,900 behind PL. Its channel has the longest history in our data and it has climbed almost without a break: about 2,500 in mid-2024, 7,000 by the start of 2026, 10,000 in June and nearly 18,000 now. It has added close to 8,000 followers since June alone.
If that pace holds, Missão will pass PL's channel soon, maybe before the second round. A new party overtaking the party of the former president on WhatsApp would say something about where the online right's attention is moving.
Why this matters in Brazil
WhatsApp is on almost every phone in Brazil, and for plenty of people it is where political content arrives, in family groups, neighbourhood groups and work groups. A channel is one of the few ways a party can post into that world openly, under its own name, and have what it sends forwarded onwards from there.
The old tactics are also harder now. Meta has tightened its anti-spam systems since 2018, which pushes parties toward things they own and sign, like a verified channel. Any organisation can set up a WhatsApp channel, and it costs nothing. PT is showing what running one seriously looks like, with daily posts, a lot of video and people who aren't politicians. It is the same thing we saw with Die Linke in Germany, whose channel grew fastest around an election and held on afterwards. We will know in a few weeks whether PT's does too.
How we counted
The follower numbers come from each channel's public preview page, read on a rolling schedule; the 28 September figures are exact. Earlier points are recovered from Internet Archive snapshots, which show rounded counts ("21K" rather than 21,000-something), and some channels have long gaps between them. We only count official party channels, and we record when we can't find one. The follower data is open under CC BY 4.0, and reporters are welcome to use the numbers and charts with credit to wha.tools.
The posting frequency, reactions and forwards are different. They are approximate figures from following the PT and PL channels during September 2026, not a systematic post-by-post count, and they are not part of the open dataset. Treat them as a reporter's notes, not measurements. Anyone can check them by opening the two channels.
