A well-connected source has just told me that it could be more serious than that.
They told me it is a concerted push to force the prime minister to drop her Chequers’ compromise.
They said: “If she doesn’t drop Chequers there will be another, then another, then another, then another”.
Mr Johnson took a while to make his mind up, arguably many months. It’s not the most dignified resignation perhaps, waiting for Mr Davis to take the lead and then pondering the pluses and minuses of a move now.
No. 10 had calculated that it could face these two resignations and might be able to survive them. But it can’t be sure. It can be reasonably sure now that an attempt on the PM’s leadership will be made. Forty-eight MPs need to send in letters demanding a vote of no confidence. That now looks very plausible.
No 10 says May will fight to keep her job if there's a no confidence vote
Downing Street has confirmed that
Theresa May will seek to fight to keep her job if Tory MPs trigger a no confidence vote, my colleague
Heather Stewart reports.