London: Senior Cabinet ministers on Sunday rallied around UK Prime Minister Keir Starmer, whose leadership is under pressure following his decision to appoint Peter Mandelson — a scandal‑tainted politician and associate of Jeffrey Epstein — to Britain’s most senior diplomatic post.

Starmer is set to face sceptical lawmakers in Parliament on Monday as he seeks to cling to his job after it emerged that Mandelson was appointed ambassador to the United States despite having failed security checks.

The prime minister has said he was “furious” to learn that he had not been informed in January 2025 that an intensive vetting process had recommended Mandelson should not be granted security clearance. The Foreign Office, which oversees diplomatic appointments, cleared him regardless.

Deputy Prime Minister David Lammy said that if Starmer had known about the vetting outcome, “he would never, ever have appointed him ambassador.”

Technology Secretary Liz Kendall told Sky News on Sunday that Starmer “is a man of integrity, and there is no way he would have proceeded” with Mandelson’s appointment had he been aware of the security concerns.

The Foreign Office’s most senior civil servant, Olly Robbins, resigned on Thursday, although Starmer’s allies say he was simply doing his job and is being made a scapegoat. Robbins is expected to give his account to the House of Commons Foreign Affairs Committee on Tuesday.

Simon McDonald, who served as the Foreign Office’s top civil servant until 2020, said Robbins had been “thrown under the bus.” He told the BBC that vetting information is highly sensitive and “would never be shared” with the prime minister or his staff.

All major opposition parties have called for Starmer to resign. Conservative Party leader Kemi Badenoch said the prime minister’s position was “untenable.” Liberal Democrat leader Ed Davey said on Sunday that the government was “in perpetual crisis” and argued it could not recover “unless Keir Starmer moves aside.”

Starmer’s Labour Party holds a large parliamentary majority, meaning any attempt to remove him would depend on his own lawmakers, many of whom are already demoralised by dire poll ratings.

Starmer survived an earlier crisis in February, when some Labour MPs called for his resignation over the Mandelson appointment. However, he could face a leadership challenge following local and regional elections on May 7, in which Labour is widely expected to perform poorly.