The public wants to know its Government has three pillars to keep it in place: firstly, that it wants to take the country in the right direction; secondly, that ministers have a basic sense of integrity; and above all, that they have the competence to keep the show on the road.
The combination of an unpopular Budget, the cash for access row and the fuel fiasco has struck all three pillars, leading to a significant drop in both the Conservative Party's poll ratings and in approval for Cameron's leadership.
Strategists in Conservative HQ will pray those poll numbers turn out to be temporary, but this does not feel like something that can be shrugged off. The wiser heads will surely concede how much has been self-inflicted - a build-up of corrective clever wheezes that ended up making the situation much worse.
The Budget's combination of abolishing the 50p top rate of tax at the same time as taxing pensioners more was never going to go down well. But the 'granny tax' got particular traction because it was the only major surprise left in the most leaked Budget in history. That sense of unfairness weakened the public's faith in pillar number one: the Government's direction.
The Budget atmosphere of favouring the richest at the expense of the majority made the revelations about the Downing Street dinners for donors particularly toxic. But to distract attention from questions about pillar number two - integrity - the Government may have ended up doing lasting damage to the most important pillar of all: competence.
The abiding sense that the problems at the fuel pump are the fault of bungling or political manoeuvring is truly awful for ministers.
Cameron's people may point to Labour's by-election loss as a reason to stay cheerful. But if the centre doesn't grasp the depth of the hole it is in, I suspect dismayed Tory MPs will soon be calling for wholesale changes of personnel in Number 10.
John Woodcock is Labour MP for Barrow and Furness, and a former spokesman for ex-prime minister Gordon Brown.