Republican Greg Gianforte celebrates with supporters after being declared the winner at a election night party for Montana's special House election against Democrat Rob Quist at the Hilton Garden Inn on May 25, 2017 in Bozeman, Montana.

Republican Greg Gianforte declared victory in Montana's special congressional election, barely a day after he was charged with misdemeanor assault following accusations that he slammed a journalist to the ground.

Gianforte, 55, a technology entrepreneur, held a 50 percent-to-44 percent lead over Democrat Rob Quist shortly after 12 a.m. ET, with nearly half of precincts reporting. Libertarian Mark Wicks had 6 percent; his vote total was less than Gianforte's margin over Quisp.