Brussels has to change if Tony Blair is to stand a chance of winning the referendum on the EU constitution, says ex-cabinet minister Stephen Byers.
Byers says voters must be shown there is no EU "conspiracy"
Mr Byers is using a speech in the Ukraine to argue that millions of jobs rest on a "yes" vote.
In a warning to ministers, he will say: "The lesson of the last few years is clear. You cannot win an argument over Europe unless you go out and make it."
Eurosceptics say the constitution gives many more powers to Brussels.
Tony Blair has rejected that claim and insisted he secured key British vetoes in his deal with EU leaders last month.
Former Transport Secretary Mr Byers will tell a conference on Saturday many Britons see the European Union as "bureaucratic, intrusive, inefficient and out of
With last month's elections showing Euroscepticism is on the increase, pro-Europeans have to persuade voters the EU is not a "conspiracy against the British people", he will argue.
Mr Byers will add: "To be in with a chance of winning the referendum in the UK, Brussels must
"It needs to be in touch with what people want and reflect their
Mr Blair performed a dramatic U-turn when he decided to allow a referendum on the constitution.
But first the treaty will go through Parliament, something which could take months.
The Tories and the UK Independence Party have pushed ministers to hold the vote straight away.