The Commons Speaker has refused a government request to hold a “yes” or “no” vote on its Brexit deal.
John Bercow said a motion on the deal had already been brought before MPs on Saturday, and it would be “repetitive and disorderly” to debate it again.
Saturday’s sitting saw an amended motion nodded through by MPs, withholding approval of Boris Johnson’s deal until it has been passed into law.
The PM’s spokesman said he was “disappointed” by the decision.
He added: “The Speaker has yet again denied us a chance to deliver on the will of British people.”
The UK is due to leave the EU in 10 days, and while Mr Johnson and fellow EU leaders have agreed a new deal to allow that to happen, it cannot come into force until it is approved by both the UK and European parliaments.
The government wanted to hold a “yes” or “no” vote – or so-called “meaningful vote” – on its deal on Saturday, but MPs instead chose to back an amendment tabled by former Tory Sir Oliver Letwin, which said that could not happen until legislation, called the Withdrawal Agreement Bill (WAB), was passed.
The WAB will be introduced later, but will then have to go through full parliamentary scrutiny in both the Commons and the Lords.
No 10 was pushing for a second shot at a meaningful vote on Monday, but Mr Bercow told the Commons he would not allow it, and had come to that decision on the basis of a parliamentary convention dating back to 1604.
He cited Parliament’s rulebook, Erskine May, which says a motion that is the same “in substance” as a previous one cannot be brought back to the Commons during the course of a single parliamentary session.
The Speaker also said the circumstances around the motion had not changed, so his ruling was “necessary… to ensure the sensible use of the House’s time and proper respect for the decisions that it takes”.