Warwick and Leamington MP Matt Western was among hundreds who voted against Theresa May's Brexit deal at the House of Commons last night.
And the Labour MP has criticised the Prime Minister for how she handled the negotiations which led to the deal.
He took to Twitter last night to say the result of 432 to 202 in favour of those voting no was "seismic",
He added: "Truth is the PM got the whole negotiation wrong.
"That’s why so many Conservatives voted against their Prime Minister.
"It is a record defeat."
The government faces a vote of no confidence instigated by a motion from the Labour Party after the Prime Minister's huge parliamentary defeat.
But it is expected to survive this with backing from Tory Brexiteers and the Democratic Unionist Party.
This will be debated in the House of Commons from about 1pm today with the vote on the motion due to take place at 7pm.
Meanwhile, European leaders have given no indication they are willing to make any concessions on the Brexit deal.