Twitter blocked conservative journalist James O’Keefe’s account on Wednesday evening, shortly after he tweeted that he was about to release new video about a candidate for the U.S. Senate.

Shortly after that tweet, O’Keefe received a notice from Twitter that his account had been blocked for twelve hours. It is not clear why he was suspended. One possibility is that a slew of false complaints, potentially from fake “sock puppet” accounts, could have triggered an automatic response.

O’Keefe’s Project Veritas has released two videos thus far this week. The first, released Tuesday, showed Manhattan Board of Elections Commissioner Alan Schulman, a Democrat, attacking New York City Mayor Bill de Blasio’s municipal ID program as rife with fraud, leading to potential voter fraud. The second, released Wednesday, showed a Clinton campaign staffer in Florida who claimed that he could “grab” the “ass” of a female fellow campaign worker and he would not be risking his job.

Twitter previously banned Breitbart Tech editor Milo Yiannopoulos after he gave the new, all-female Ghostbusters film a negative review. Twitter cited racist tweets sent to Ghostbusters actress Leslie Jones by other people, though the actress herself has used racist language on Twitter.

On Tuesday, Prager University (PragerU), an educational project of conservative talk radio host Dennis Prager, reported that YouTube is restricting access to 21 of its videos. The videos included:

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. His new book, See No Evil: 19 Hard Truths the Left Can’t Handle, is available from Regnery through Amazon. Follow him on Twitter at @joelpollak.