One of the architects of New Labour has called on shadow cabinet members to raise their game as all the party leaders, including Nicola Sturgeon, gear up for next year's general election.

The Deputy First Minister will join David Cameron, Ed Miliband, Nick Clegg, Nigel Farage and the leaders of the Greens and Plaid Cymru for a sit down interview with the BBC's Andrew Marr early next year.

Mr Cameron is to also visit the White House within weeks, in a visit expected to include a pre-election photo call with President Obama, it emerged over the weekend.

But the Conservative leader suffered a blow after a poll put Labour in the lead by seven points following this month's autumn statement.

Mr Mandelson appeared to criticise some in the shadow cabinet as he called on them to work "as a team" and, crucially, set out where they would cut spending next May.

He also indicated he would like to see leader Ed Miliband's older brother - and former rival - David return to British politics.

Labour has announced plans to cut the deficit every year of the next parliament and get the current budget into surplus as soon as possible.

But Lord Mandelson said that there was no point leaving it to Mr Miliband and shadow chancellor Ed Balls "to make these statements. The shadow cabinet as a whole have got to play as a team in this."

He added: "Each and every one of them has got to make clear that we will cut spending across government where we have to, but we will also invest where we need to."

Tory chairman Grant Shapps said Lord Mandelson's comments on the Labour frontbench show "how little faith" Labour figures have in Ed Miliband.

"Even Peter Mandelson accepts that Miliband is a weak leader who is unable to lead his shadow cabinet," Mr Shapps said.

"And if he can't run his own team, he clearly isn't fit to run the country."

Several polls since the Autumn Statement have shown Labour with an increased lead.

The Opinium survey for the Observer put the opposition seven points ahead of the Conservatives, while a YouGov survey gave Labour a two-point lead.