MEXICO CITY (AP) — Mexican officials condemned the weekend killing of a would-be candidate for mayor in a small town in the southern state of Oaxaca. Analysts said Monday 18 pre-candidates have been killed so far in the run-up to the June mid-term elections. They were killed before they opened formal campaigns. The killings have come mainly in violence-plagued states like Veracruz, on the Gulf coast, and Guerrero, on the Pacific. But isolated killings have occurred in a half-dozen other states. While motives vary in cases that have been solved, politicians in Mexico face threats from drug cartels, political rivals and corrupt police.