Million-dollar campaigns, saturation advertising and massive canvassing have become commonplace in U.S. elections, especially in a swing state such as Colorado. A campaign underway there has all of the above – in a recall vote for two state senators that has become a showdown over gun policy and political dominance in a changing state.

COLORADO SPRINGS — Mayor Michael R. Bloomberg of New York and the billionaire philanthropist Eli Broad have each donated hundreds of thousands of dollars. The National Rifle Association is buying political advertisements. New York’s junior senator sent a fund-raising e-mail. And the election has attracted news coverage from as far away as Sweden.

Twelve people lost their lives last year when James Holmes, profusely armed and dressed like the Joker, sprayed Aurora moviegoers with bullets while The Dark Knight Rises played out on the screen. A reporter on this site wrote that the gun control laws passed in this year’s legislative session “came in reaction to the random massacres” in Aurora and Connecticut.