To date, David Cameron has avoided his own version of Nick Clegg's tuition fees moment: a profound breach of trust that inflicts permanent damage on his party. But with increasing evidence of an unprecedented A&E crisis, the NHS could provide it.
After Ed Miliband challenged him on the subject at yesterday's PMQs, Labour has released a new attack video, set to a Jaws-esque soundtrack, reminding voters just how much emphasis Cameron put on protecting the health service before the election. Noting that the public rank the NHS as the most important policy area after the economy and immigration, one senior figure told me yesterday that the party intended to put the issue "back at the top of the agenda".
Despite a concerted attempt by the Tories to pin the blame for the Mid-Staffs scandal on the opposition (including a lengthy section in Cameron's conference speech) , Labour retains a double-digit lead on health. One party source told me that focus groups reacted "particularly strongly" when they were reminded of Cameron's past pledges on the NHS.
If not the "split-screen moment" that No. 10 has long sought to avoid (when footage of a politician saying one thing is run alongside footage of them saying the reverse), the video is the closest Cameron has come to suffering this wound.
The Tories will seek to avoid the blame for the A&E crisis by arguing that the NHS has long-standing problems that afflict all governments, aiming to scrape a messy draw with Labour. But their decision to impose Andrew Lansley's reorganisation on the service (for which they had no mandate) makes that task significantly harder.
If the bad news on the economy appears to have passed, the danger for the Tories is that the bad news on the health service is just beginning.