Chris Simcox, at a news conference outside the state Capitol in Phoenix, attacked McCain on immigration, blaming him for recent violence along the border with Mexico, The Arizona Star reported. But he also promised not to run a "one-issue" campaign.
"He is fully responsible for the deaths along our borders, the raging violence in Mexico and the violence that we have in the streets of U.S. cities from border to border, coast to coast," Simcox said.
Simcox is still president of the Minuteman Civil Defense Corps, which stages patrols of the border area looking for illegal border crossers. He described the group as "working class, middle class working Joes."
McCain, 72, is in his fourth term in the Senate. In 2004, McCain received 77 percent of the vote against a little-known Democrat, but he has won all his elections by healthy margins.