KANSAS CITY, Missouri (Reuters) - Democratic Missouri Senator Claire McCaskill holds a slim lead of 2 percentage points over Republican challenger Todd Akin - essentially a deadlock - in a race being closely watched following Akin's controversial comments on "legitimate rape," a poll released on Saturday showed. McCaskill had been seen as one of the most vulnerable incumbent Democrats but has led Akin in most polls since he said in August that women could biologically defend themselves against pregnancy caused by "legitimate rape." Akin said later he misspoke when he made the remark, which led to widespread rebukes even from...