Other fake accounts have been traced to Russian-backed agents that the U.S. government says are working to sow political discord in the country. Researchers say as many as 15 per cent of users could be fake, a number Twitter says is much lower.
It's unclear if the latest loss of followers is related to bots. A Twitter spokesperson didn't immediately return a request for comment.
Conservatives have long accused Twitter of targeting them specifically. Even Ajit Pai, the chair of the Federal Communications Commission, has said the service discriminates against conservatives.
On the flip side, progressive users say Twitter doesn't do enough to stop harassment against women and people of colour. Some argue President Donald Trump, Twitter's most influential users, should be banned for bullying opponents.