BILLINGS, Mont. (AP) — The struggle for control of Montana's largest publicly-traded company is turning increasingly bitter ahead of a May 2 shareholders' vote.

Former Gov. Brian Schweitzer and a team of dissident investors are sparring with Stillwater Mining executives over who could better lead the company.

The stakes for Schweitzer are high, complicated by his considering a run to replace U.S. Sen. Max Baucus. Success would allow Schweitzer to launch a Senate campaign on a high note. Defeat could tarnish his much-touted business credentials.

Dueling campaigns to sway public opinion on Stillwater have included sharp personal attacks from both sides, and forced Stillwater Chairman Frank McAllister to return $2.3 million worth of company shares following a shareholder's lawsuit.

Stillwater employs 1,664 people and operates two precious metals mines in the Beartooth Mountains.