Attorney General Merrick Garland warned Monday of mounting violent threats against election workers across the country, and vowed that the Justice Department will be “relentless” in prosecuting those who threaten the democratic process.

Speaking to reporters ahead of a meeting of the department’s Election Threats Task Force, Garland cited a handful of cases over the past several years in which poll workers in Arizona, Michigan and Georgia — swing states in the presidential election — have faced death threats. In each instance, he said, federal prosecutors won convictions against the perpetrators and sentences of up to 3½ years in federal prison.