WASHINGTON — Milo Yiannopoulos, the provocateur and Breitbart News editor, was under pressure on several fronts Monday after the publication of a video in which he condones sexual relations with boys as young as 13 and laughs off the seriousness of pedophilia by Roman Catholic priests.

The organizers of the Conservative Political Action Conference rescinded their invitation for him to speak later this week. Simon & Schuster said it was canceling publication of his forthcoming book, “Dangerous.” And there were calls online for Breitbart to sever ties with him.

The episode, which unraveled quickly online over the weekend, put many conservatives in a deeply uncomfortable position. They have long defended Mr. Yiannopoulos’s attention-seeking stunts and racially charged antics on the grounds that the left had tried to hypocritically censor his right to free speech.

But endorsing pedophilia, it seemed, was more than they could tolerate. The board of the American Conservative Union, which includes veterans of the conservative movement like Grover Norquist and Morton Blackwell, made the decision to revoke Mr. Yiannopoulos’s speaking slot and condemn his comments on Monday.

“We initially extended the invitation knowing that the free speech issue on college campuses is a battlefield where we need brave, conservative…