Mandelson's 2005 general election warning to Blair about rival Brown
Released Government files showed Tony Blair was told that tensions would need to be "carefully managed"
Former US ambassador Peter Mandelson warned Tony Blair not to allow Gordon Brown to wreck Labour's 2005 general election campaign, according to new files.
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Relations between Blair and his then-Chancellor were strained by late 2004 as Labour prepared to try for a third successive election victory.
However, Brown and his allies believed the then-Prime Minister had gone back on his promise to step down towards the end of the party's second term to allow him to take over.
In one Government file released to the National Archives in Kew, west London, Lord Mandelson warned Blair that such tensions would need to be carefully managed during the election campaign.
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Mandelson wrote to him: "A big issue will be you personally. The media will want to bring pressure on you to a new level of intensity. Next door [Brown] will want a good majority but will not want you to do well."
He also warned Blair to be cautious about including Brown's people in the election campaign, saying that it would be a challenge to agree "where GB's people can be included without giving them a veto or scope for insider demolition."
The pair temporarily patched up their differences during the subsequent election campaign, but tensions re-emerged the following year after Labour was back in office.
Mandelson also advised to keep Alastair Campbell away from frontline operations, after he had stepped down as No 10 communications chief.
He told Blair: "You must be conscious of the need to create reasons for them to come back on side. Avoid things that will antagonise them (therefore be careful about AC – he is indispensable but must be equally invisible)."
Blair eventually announced his resignation in 2007 following a rebellion of Labour MPs who forced his hand amid sustained political pressure over the Iraq War.
On the day of the election win, cabinet secretary Andrew Turnbull also warned about the state of ministerial talent coming through.
Turnbull told him: "If you think of yourself as a football manager who has no money for transfers and is reliant solely on graduating people through the academy, you have cause to be worried.
"The resources you have coming through suggest we are not doing enough to train new entrants beyond traditional on-the-job apprenticeships.
"I think we should look at some new initiatives to get new ministers trained to think more strategically and operate more professionally."
The younger figures at the time included the former Labour leader and current energy secretary Ed Miliband, and Andy Burnham, now the mayor of Greater Manchester.