Richard Ziser became active in Nevada politics in 2000, when he served as chairman of the Coalition for the Protection of Marriage, which sought to amend the Nevada Constitution to define marriage as only between a man and a woman.
Voters approved the proposal by a 70-30 percent margin in 2000 and again in 2002 by a 67-33 percent margin. Backers say the constitutional provision was needed to protect Nevada from having to honor civil unions of gay couples in other states, which critics said it amounted to anti-gay bigotry.
The group raised about $2 million in its successful efforts to amend the constitution.
Ziser's U.S. Senate bid is his first race for elective office. He won his four-way Republican primary by a nearly 2-1 margin over his closest rival, getting 34 percent of the ballots cast.