A nuclear option would be to call a no-confidence vote in his own government.
“It would get him to where he possibly wants, there would be a general election, unless within 14 days his or another government can secure a confidence vote,” said Ruth Fox, the director of the Hansard Society, a leading constitutional research organization.
However, she points out the absurdity of that situation: “It would be extraordinary for a government to lay a motion of no confidence in itself and encourage [its] party to vote for that.”
Aside of being potentially embarrassing and completely unprecedented, the move could also run afoul of the UK’s unwritten constitution.
The Fixed-term Parliaments Act doesn’t explicitly forbid Johnson from calling his own no confidence vote. But when that law was being passed in 2011, the then Conservative minister for constitutional reform Mark Harper said such a move would be “absolutely unconstitutional” and warned that “public would not respond well to a government behaving in that way.”