Rishi Sunak has said he wants to leave the EU and is the fifth Yorkshire MP to back the out campaign.
Mr Sunak, who was elected in May 2015, spent four days considering his decision after David Cameron returned from the EU Council with a raft of proposals for a reformed EU.
However he won't be backing the Prime Minister in the run up to the June 23 referendum, instead
He wrote on his Facebook account this morning: "After much thought I have decided to vote for Britain to leave the EU. Now to sit down and set out to my constituents the reasons for my decision."
The successor to William Hague - who this week warned MPs against division on the issue - is understood to have concerns about immigration as well as the economic impact of remaining in the EU.
After attending Stanford University in the USA and a successful career in business, the father-of-two moved his family to Yorkshire last year to begin his political career.
He will now write to his constituents personally to explain more about his decision and his full reasoning will be released towards the end of the week.
Speaking in the European Parliament today, European Council president Donald Tusk tried to counter claims the deal struck with the UK was not legally binding.
He described the agreement struck after marathon talks in Brussels last week as a “legally binding and irreversible settlement” that “cannot be annulled by the European Court of Justice”.
Mr Tusk also appeared to follow David Cameron in warning there would be no fresh negotiations in the event of a ‘leave’ vote, saying if that happened the deal would “cease to exist”.
He added: “The European Union will respect the decision of the British people. If the majority votes to leave, that is what will happen.It will change Europe forever and it will be a change for the worse.”
More to follow.