Theresa May looks increasingly likely to face a confidence vote with further speculation that 48 letters have been submitted to the 1922 committee.
On Tuesday evening Owen Paterson, former Northern Ireland and environment secretary, became the latest Conservative MP known to have sent a letter to committee chair Sir Graham Brady.
Earlier in the day, European Council president Donald Tusk told Mrs May that the EU wants to help get her Brexit deal through the Commons but added: "The question is how."
The Prime Minister embarked on an emergency tour of Europe on Tuesday to try to win reassurances on the Northern Ireland backstop after deciding to defer the Commons vote on her Brexit deal to avoid a humiliating defeat.
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