Hillary Clinton's fellow party members are getting nervous. It may just be a twitch of the eye, a whisper — but they're getting nervous. The former secretary of state is currently regarded as the Democrats' only serious candidate for Obama's succession. She has a reputation for persevering; she is political stamina personified.

But she lacks a political highlight — a success that only she, and nobody else, could have achieved. When Clinton's former spokesperson was asked to name the secretary's main achievement, nothing immediately sprang to mind. In political terms, Hillary Clinton's starting position for the 2016 candidacy is primarily her reputation for not having done anything wrong as secretary of state.

But now she may have done something wrong. As secretary of state, she used at least two private e-mail addresses while in office. That in itself is not illegal. It does, however, contradict guidelines on entrusting official secrets to private e-mail systems. Clinton had previously dismissed an ambassador on such grounds. Now she herself is being exposed.

Clinton and Guccifer, the Hacker

Clinton wants to disclose most of her e-mails, but she doesn't have unlimited freedom in the selection process. Some time ago, the Romanian computer hacker "Guccifer" hacked into Clinton's private e-mail account and published a selection of the contents. As a result, it emerged that a confidant had supplied the secretary with assessments of Libya, and apparently also Angela Merkel, via the unsecured channel.

Clinton's opportunity lies in promoting the image of the new — the image of the first female president in U.S. history. She had already emphasized this in 2008 against Obama, and failed. She is now part of the establishment. The era of her husband, Bill Clinton, 20 years ago was characterized by brilliance, but also by prevarication. The private e-mail account may be a stronger reminder of this tendency to prevaricate than would be good for a candidacy.