The Tory leader will use a meeting of centre-right parties in Marbella to urge MEPs to unite behind the party's recent European elections manifesto. In his speech, Mr Hague will say: "So my message to you is simple: don't go native. Work with our allies in the European Parliament to fight socialism.
"Work with each other as a united group to fight for our manifesto. Work with the whole of the Conservative Party to keep the pound."
Mr Hague infuriated Tory Eurosceptics last week when he announced that his party would remain allied to the federalist centre-right grouping in the European Parliament. He succumbed to pressure from pro-European MEPs and persuaded the Shadow Cabinet to approve a plan to maintain loose affiliation to the European People's Party (EPP).
The decision will create a coalition that can wrest control of the Parliament from the Socialist group and allow Tory MEPs to take chair important committees in Strasbourg.
Mr Hague will tell MEPs that his agreement for continued loose links with the EPP would ensure that MEPs had influence in the Parliament. He will also urge a "fresh start" for the relationship between MEPs and Westminster to put an end to previous splits over the European Union within his party.
"I will expect and demand that all Conservative MEPs vote together as a single group for the manifesto on which you were elected. No exceptions. No two-way or three-way splits," he will say.Reuse content