Hillary Clinton does her best not to leave anything to chance. Every word she utters and every position she takes has been poll-tested and focus-grouped to attract the most votes. In most years that calculated approach would be a strength. But the cloud of scandal casting a shadow over this year’s campaign has made her appear flat-footed.

That’s not the perception that Clinton expected to carry with her into the first debate, a debate that has taken on newfound importance given the rise of challenger Bernie Sanders and the possible campaign of Vice President Joe Biden.