Lord Glasman has launched a scathing attack on the Prime Minister, declaring that the controversy surrounding Peter Mandelson has escalated "from a mistake into a calamity".
The Labour peer told GB News it is now "obvious" that Sir Keir Starmer cannot fulfil the demands of his role.
Lord Glasman, who has previously been a supporter of the Prime Minister, said he had hoped Sir Keir could deliver national renewal but acknowledged there comes a point when difficult judgements must be made.
He stated: "Sometimes you've got to say to someone that you thought they could do the job, but it's obvious they can't.
"And that's where we are at the moment."
The peer revealed he had written a memorandum during Donald Trump's inauguration warning that the decision was an evident political blunder.
He emphasised that concerns about Lord Mandelson extended far beyond his association with Jeffrey Epstein, noting that "the whole country knew" about his consultancy firm Global Counsel's involvement with Russia and China.
Lord Glasman referenced widely circulated images showing Peter Mandelson "blowing out the birthday candles and wearing his dressing gown with Jeffrey Epstein".
Lord Glasman has declared that Keir Starmer is 'obviously not up to the job'
|PA / GB NEWS
The fundamental problem, he argued, was the failure to acknowledge the error.
He said: "In life, as is lived by normal people, it's when you make a mistake, you own the mistake, you apologise and you do something about it."
The political consequences have been severe, with Morgan McSweeney forced to leave Downing Street as a result of the affair.
Lord Glasman described McSweeney as "a force for sanity in Number 10" whom he greatly respected, adding that further resignations and dismissals have followed.
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The peer criticised Starmer's handling of the crisis as characteristic of a lawyer rather than a politician.
He suggested the Prime Minister is constructing a legal defence while facing a similar approach from Olly Robbins, warning this will descend into procedural arguments.
"The abdication of responsibility and the turn to procedure is really not the way ahead," Lord Glasman said. "Politicians should govern and make decisions in our sovereign democracy."
Lord Glasman expressed deep alarm that the ongoing controversy is paralysing the Government while urgent matters demand attention.
Lord Glasman told GB News his 'beloved' Labour Party is 'not giving our country the Government that it needs'
|GB NEWS
He pointed to conflicts in Ukraine and Iran, decisions required on the economy and energy policy, and the state of Britain's armed forces.
"All I hear is Peter Mandelson, and this is blocking effective Government," he said. "We can't move. It feels like Government is static and it's ad hoc."
The peer voiced frustration that Labour has failed to halt Channel crossings, retreated from welfare reform, and shown no evidence of an industrial strategy.
"My beloved Labour Party is not giving our country the Government that it needs," he concluded.