The Tories may claim Labour is in the pocket of the unions, but not all of them are welcome at No 10. The Trade Unionist and Socialist Coalition, a new left-wing alliance, plans to field candidates in 38 seats and has won the support of Bob Crow, RMT general secretary.
Labour veterans such as David Blunkett, standing in Sheffield, will find themselves up against a familiar foe. The Socialist Party, which leads the alliance, is the successor to the Militant Tendency. The coalition is unlikely to win any seats but it may split the Labour vote in just the sort of constituencies the Tories are looking to win.
Before Michael Ashcroft became known as the man who bought the Conservative Party, that title was held by Stuart Wheeler. A businessman who made a fortune through spread-betting, he gave £5m to the Tories in 2001 - the largest-ever donation to a British party - but was expelled by the leadership last year after donating £100,000 to Ukip. Now, he has set up the Trust Party and plans to stand against the Bexhill MP Greg Barker, an ally of David Cameron's.
He is challenging Barker, the shadow climate-change minister, on his environmentalism and his expenses - Wheeler has pledged, if elected, not to claim any.
Friends in the north
The alliance between the Tories and the Ulster Unionists has claimed its first victim. Sylvia Hermon, the Ulster Unionists' only MP, has resigned in protest and now plans to defend her seat as an independent. Hermon has consistently voted with Labour at Westminster and fears the Tories' planned spending cuts will harm Northern Ireland's poorest areas. She may retain the seat, where she has a majority of 4,944, through a pact of her own. It is thought that the DUP will stand aside and endorse her candidacy.
The Greens have displayed their growing strength by winning a shock victory in a council by-election. Rachel Eburne won a seat from the Conservatives on Mid Suffolk District Council with 61 per cent of the vote - a 33.2 per cent swing. The success will raise hopes that the party is about to win its first Westminster seat. The Green leader, Caroline Lucas, is the favourite in Brighton Pavilion. Her deputy, Adrian Ramsay, is expected to run Charles Clarke close in Norwich South.