Peers including the Archbishop of Canterbury are set to publicly savage the Tories' controversial illegal migration bill as it faces its first test in the House of Lords.
Justin Welby - fresh from his central role in the King's Coronation ceremony - will reportedly condemn proposals to give ministers powers to deport asylum seekers crossing the Channel.
The head of the Church of England has previously slammed the Government's plans to send those seeking asylum to Rwanda, saying the policy did not stand the "judgement of God".
He has also hit out at the Home Secretary Suella Braverman's "harmful rhetoric" as she faced outrage for suggesting the UK was facing an "invasion" of asylum seekers.
According to the i newspaper, Dr Welby will use the first debate in the upper chamber on Rishi Sunak's legislation to condemn the flagship plans to "stop small boats".
He is among almost 90 peers listed to speak on Wednesday to debate the plans described as "racist and xenophobic" by Amnesty International UK.
In a letter to members of the House of Lords, the organisation's chief executive Sacha Deshmukh urged them to reject the bill - a "blatant breach" of the UN Refugee Convention.
“The Lords should reject this squalid bill and speak up for all those horrified by this Government’s cruel asylum policies," he added.
Liberal Democrat Lord Paddick has also proposed a so-called fatal motion to the proposed legislation, aimed at stopping it in its tracks at its first Lords hurdle.
His amendment argues the draft legislation would see Britain fail to meet its international law commitments, allow ministers to ignore the directions of judges and undermine "the UK's tradition of providing sanctuary to refugees", while failing to tackle the backlog of asylum cases or people smuggling gangs.
However, the blocking bid is destined to fail without the backing of the main opposition.
It comes as the Home Secretary used an article in The Times to remind the upper chamber that MPs passed the legislation, claiming it is "designed to meet the will of the British people in a humane and fair way" and she urged them to support it.
