Enough already. Hillary Clinton has not even launched her 2016 campaign, yet exhaustion has already set in. Neither official nor unofficial, her putative White House bid inhabits the worst of both worlds. It occupies a half-light in which everyone knows she plans to run yet she can still cite privacy to duck the hard questions.

Last week’s press conference did her no favours. Mrs Clinton’s aim was to quell the crescendo over her use of a private email account for official correspondence when she was US secretary of state. Her performance raised more questions than it answered. Mrs Clinton’s miscue underlined two imperatives. First, she must declare her candidacy as soon as possible. Second, she must accept that such grilling is an unavoidable ordeal for all candidates. The longer she prevaricates, the more shrill it will become.

To be sure, there were tactical advantages to having delayed her launch. The Republican field is already crowded with hopefuls: more than 20 at the latest count. There are benefits to watching them fight it out. Moreover, Mrs Clinton is unlikely to face any serious rival for the Democratic nomination. The only names to have cropped up — James Webb, the former Virginia senator, Bernie Sanders, the “socialist” Democrat from Vermont, and Martin O’Malley, the ex-governor of Maryland — are marginal figures. None is likely to make Mrs Clinton feel the heat.