Dick Leinenkugel (R) ended his campaign to unseat Sen. Russ Feingold (D) less than one month after announcing it.

Leinenkugel, a former brewing company executive and state commerce secretary, made his surprise announcement Sunday at the Wisconsin Republican Party’s convention. He said he would back businessman Ron Johnson, who began his campaign earlier this month.

In a campaign statement posted on Wispolitics.com, Leinenkugel said that “spending millions on a divisive primary campaign only serves to give an advantage to Russ Feingold.”

Also seeking the Republican nomination are real estate developer Terrence Wall and businessman Dave Westlake.