Mexicans in nearly half of the country’s states will head to the polls today to elect new governors and local officials. But many of the candidates they might once have voted for never made it to the ballot after the bloodiest campaign in 15 years. In Tamaulipas, the favorite for the governor’s seat was gunned down in his car this week. And elsewhere, a mayoral candidate was shot dead, many others stepped down, and some 550 electoral officials resigned. The drug cartels that have wreaked havoc across the country are being blamed for the chaos. "We're a bit nervous, but we have to go out to vote because it's our only weapon for the future," said one voter in Nuevo Laredo. The vote is also being seen as a referendum on President Felipe Calderon’s crackdown on gangs, which began over three years ago and sparked an unending string of attacks.