If you're old enough to remember this is all too familiar, the perception of alleged sleeze within government.
Donations to a party which seem to be, well, not done in the correct manner.
John Major's government crashed and burned for this.
An unhinged wheel that left the central political carriage unusable.
That whiff has now surfaced.
And what made it worse for Major was the perceived contempt for the electorate.
The PM has called an inquiry, but he will know that in politics perception is everything, and it'll take a cabinet war room PR excercise to undo this states of affairs.