HELENA – A Billings, Montana, attorney says he will run to unseat newly elected U.S. Rep. Greg Gianforte in next year’s election.

John Heenan becomes the first Democrat to register a campaign committee to challenge the Bozeman Republican, who garnered wide attention after a bizarre election-eve assault on a reporter on May 24.

In announcing his bid Monday, Heenan said he would use his experience as a consumer protection lawyer to advocate for Montanans.

Gianforte has already announced he would seek re-election.

Heenan said he would partly focus on increasing access to “quality, affordable health care.”

Heenan was among the team assembled by the commissioner of political practices last year to prosecute former state Rep. Art Wittich, a Republican from Bozeman, for campaign finance violations.