On October 31, 2013, thousands of Twitter accounts, automated to actively retweet President Nicolas Maduro of Venezuela, were unexpectedly closed by the social media platform. I exploit this event to study the relationship between perceived popularity on social media (amplified through the use of bot accounts) and online political expression. The analysis uses more than two hundred thousand tweets spanning six months around the event and employs a quasi-experimental empirical framework. Following the closure of the accounts, the volume of tweets mentioning the president increased by an estimated 33 percent, with a differential increase for critical messages. Relative to tweets by government leaders, the number of likes for tweets by opposition leaders increased by an estimated 21 percent. Consistent with the presence of a spiral of silence in online political expression, the results suggest that the change in the perceived popularity of Maduro led to an increase in users’ willingness to express both criticism of the president and support for the opposition. While previous studies have documented how autocratic governments engage in manipulative online campaigns, this paper provides evidence of their effectiveness and highlights an important mechanism through which they can influence behavior.