The public
Ultimately it seems unlikely the prime minister would resign. Instead his fate rests in the hands of his MPs.
It takes 54 of them to demand a no confidence vote in his leadership before a contest can be triggered.
Johnson being fined by police for breaking Covid laws did not cause that threshold to be met. And so far as is known, neither has the Gray report. And even being found to have misled the Commons might not be enough.
But that might change if Conservative MPs believe Johnson is no longer the election winner he once was.
In June, there will be two by-elections, probably on the same day. The 23rd is seen as the likely date.
Wakefield in Yorkshire and Tiverton and Honiton in Devon will be electing new MPs. Both are currently held by the Conservatives.
But the party risks losing Wakefield to Labour and Tiverton to the Lib Dems amid a spiralling cost of living crisis and any fallout from partygate.
The contest in Wakefield was triggered after Conservative MP Imran Ahmad Khan was convicted for sexually assaulting a boy.
The Tories won the seat by 3,358 votes in 2019, until then it had been held by Labour since 1932.
In Tiverton, a by-election was triggered after Tory MP Neil Parish quit over revelations he watched porn on his phone in the Commons chamber.
Parish won the seat in 2019 with a healthy majority of 24,239 over Labour, and it has been Conservative since its creation in 1997.
But while Labour is currently in second place, the constituency had for many years been a close fight between the Tories and the Lib Dems.
The Lib Dems, boosted by the capture of neighbouring Somerset council in the local elections earlier this month, are hoping for a resurgence in their former south west heartland.
The party is aiming to repeat its success at the recent North Shropshire by-election, where it overturned a 23,000 Tory majority held by disgraced MP Owen Paterson.
If the Conservatives lose both seats, Tory MPs might decide Johnson is leading them to a general election disaster and move against him. Or n