McALESTER, Okla. — Oklahoma's last execution went so badly that the state tried to cancel it before it was over. With the inmate writhing while the lethal drugs seeped into his body, his executioners drew the viewing gallery curtains, concealing what the warden later described as "a bloody mess." The botched execution of Clayton Lockett in April and other troubling ones this year in Ohio and Arizona gave capital punishment opponents a flicker of hope that areas of the country that most enthusiastically support the death penalty might have a change of heart.