At the helm
NO Lord Owen
Lord Owen chairs New Europe, the pro-European, anti-euro group. With his statesmanlike credibility, he represents the acceptable face of the No movement. Moderate Europhobes have high hopes that he will keep the media spotlight off the Tories.
NO Iain Duncan Smith
The Tory leader has doggedly refused to make the euro an issue for his party; Central Office doesn't want to repeat the disastrous "Save the Pound" election campaign of 2001. However, IDS cannot avoid the issue forever, because the result of any referendum will be a defining moment for his leadership.
YES Tony Blair
Victory means his place in history - and perhaps a stepping stone to a future "presidency of Europe". But Blair does not fight for lost causes and the referendum will happen only if poll figures point to success.
YES Gordon Brown
Brown has always allowed himself to be seen as the enigma of the euro debate. But if he gets a positive assessment based on the five tests, the Chancellor will ensure that he and Blair get an equal role in the campaign.
In the engine room
The No campaign comprises two groups: New Europe (the "Europe yes, euro no" group) and Business for Sterling (BfS).
Janet Bush directs New Europe. This former economics editor of the Times is both media-savvy and economically literate. She adamantly denies any links to the Tories.
George Eustice leads BfS. His appointment caused controversy when it was revealed that he had stood as a UK Independence Party candidate in the 1999 European parliamentary elections.
His predecessor, Dominic Cummings, now heads Tory strategy. Cummings recently embarrassed IDS by saying that "the biggest potential threat to the pound's survival is the Conservative Party".
Britain in Europe (BiE) leads the Yes campaign, as the single major umbrella group with cross-party support. It boasts a small rump of Tories: not only Kenneth Clarke and Michael Heseltine, but also several back-room boys.
Critics, however, still see BiE as a tool of Blairism. The director, Simon Buckby, helped to run Labour's 1997 general election campaign and critics dismiss him as a party apparatchik. The BiE board also includes new Labour luvvies such as Lord Simon of Unilever, Adair Turner of Merrill Lynch and Sir Ken Jackson, head of the union Amicus. Jackson, Blair's favourite unionist, and seen as a pace-setter for the euro, recently proclaimed that a referendum is "very, very near".