Special report - How Republicans are using immigration to scare voters to the polls

Members of the International Boilermakers Union Local D239 and their supporters outside Imerys Talc America Inc. in Three Forks, Montana, U.S., October 13, 2018. REUTERS/Jim Urquhart

INDIANAPOLIS, Indiana (Reuters) - The commercial opens with an appeal to fear: a hoodie-wearing man prowling an alley, knife in hand. His face remains hidden but the ad makes it clear: He’s an illegal immigrant.

“We need tough immigration enforcement to keep dangerous criminals out,” says the ad by a national conservative political group, part of an effort to help a Republican challenger, Mike Braun, oust a Democratic incumbent in Indiana and capture a U.S. Senate seat in November’s congressional elections.