In Toronto, a candidate in this week’s mayoral election who vows to clear homeless encampments released a set of campaign promises illustrated by artificial intelligence, including fake dystopian images of people camped out on a downtown street and a fabricated image of tents set up in a park. In New Zealand, a political party posted a realistic-looking rendering on Instagram of fake robbers rampaging through a jewelry shop. In Chicago, the runner-up in the mayoral vote in April complained that a Twitter account masquerading as a news outlet had used A.I. to clone his voice in a way that suggested he condoned police brutality. What began a few months ago as a slow drip of fund-raising emails and promotional images composed by A.I. for political campaigns has turned into a steady stream of campaign materials created by the technology, rewriting the political playbook for democratic elections around the world.