TONY Blair's election campaign was dealt a blow last night as it emerged a Labour Party stalwart will resign today in a show of support for the independent candidate standing against the Prime Minister.

Derek Cattell will formally resign from the Sedgefield Labour Party this morning after being a member for 30 years.

In a letter to constituency secretary Rita Taylor, he said he was unwilling to support the re-election of Mr Blair as Sedgefield's MP and questioned the Prime Minister's "honesty and integrity".

And he will sign the nomination papers of Reg Keys, who is standing against Mr Blair in the Sedgefield constituency.

Mr Keys' son, Lance Corporal Tom Keys, was one of six military policemen killed in an ambush in Iraq, in June 2003.

Mr Cattell, who was a member of the constituency's Labour Party executive committee for nine years, said it had been a difficult decision to make.

He said: "For some time I have been increasingly concerned by a number of issues presided over by Tony Blair, none more so than the decision to take us to war in Iraq.

"Although I wish to see a Labour government in office, I am unwilling to vote or work for the re-election of Tony Blair as Sedgefield's MP. Therefore, I feel I have no alternative but to resign my Labour Party membership."

He revealed his support for Mr Keys, adding: "Tom and 84 other soldiers lost their lives along with thousands of Iraqis in a needless war for which Tony Blair was a major architect."

Mr Keys told The Northern Echo last night: "I realise how hard it has been for Derek to take this step and I deeply appreciate that someone of Derek's stature and history has placed his trust in me."

Mr Cattell's defection is bound to cause an upset in the Blair camp. A staunch labour supporter, he served as a regional officer for the GMB union for 20 years until his retirement last year.

He hit the headlines fighting the closure of North-East companies including Black and Decker, in Spennymoor, and Sara Lee Courtaulds, in Bishop Auckland, both County Durham.

Last night, the GMB, which is a Labour supporter, said it recognised there was a lot of strong feeling against the decision to invade Iraq. A spokesman said: "The GMB recognises the strength of feeling of people like Derek, who has been the backbone of the Labour movement for many years.

"The Labour Party will have to work hard to regain their trust. But the GMB believes that the return of a Labour government is the only way to ensure that the Tories never get back into power. That would be a disaster for the working people."

Mr Blair's agent, John Burton, condemned Mr Cattell's decision and backed the Prime Minister on the Iraq war.

He said: "As a strong union man Derek needs to remember what the Labour Party has done for the ordinary trade union man.

"He should come to me before he resigns and I will tell him exactly how he can trust Tony Blair and how everything that has been said about Iraq is rubbish."

Former MI5 officer David Shayler said he would not stand against the Prime Minister and would be backing Mr Keys. He has also urged all other candidates standing in Sedgefield to withdraw and give Mr Keys a clear run.

Also standing for election are William Brown, UK Independence Party, Robert Browne, Liberal Democrat, Jonathan Cockburn, Blair Must Go Party, Helen John, Independent, Al Lockwood, Conservative, Fiona Luckhurst-Matthews, Veritas, Baroney Maroney Staniforth, Monster Raving Looney Party.