Suella Braverman's "gimmick" attempt to tackle small boat crossings is set for a mauling by peers - with a high-profile Lord calling for it to be thrown out altogether.
Dozens of them will tomorrow demand changes to the controversial Illegal Migration Bill, which if passed would see everyone who arrives by small boats detained and deported.
Critics say the plan is unworkable and unethical, and the Government is braced for the proposals to take a battering in the House of Lords.
Former I'm A Celebrity Get Me Out of Here contestant and ex-deputy assistant commissioner of the Met Police Lord Paddick has called for the bill to be denied a second reading.
The Lib Dem peer said it shouldn't proceed as it doesn't meet the UK's international law commitments and doesn't address the problems it's supposed to solve.
There is expected to be widespread opposition to measures that would make it easier for the Home Secretary to overrule court rulings in a bid to speed up deportations.
The Government has already faced opposition to the legislation - which would deny refugees protection under human trafficking laws - in the Commons, as it tries to tackle a massive backlog of asylum applications.
A Labour source in the Lords said: “The range of Peers who’ve signed up for Second Reading is an indication of the wide concern that exists with this legislation, and the tough scrutiny and challenges it will face in the months ahead.
“The small boats crisis needs tackling head on but this gimmick of a Bill won’t deal with the major problems and misery caused by those who traffic and exploit vulnerable people, risk lives, and undermine our border security.
"And the headlong rush to get it on the statute book will also see genuine asylum seekers stuck in a semi-permanent limbo while the backlog of claims gets longer and longer."
Questions have been raised over whether the measures included in the bill are legal.
The Government faces pressure to expand safe and legal routes for refugees seeking sanctuary in the UK.
The source said: “There is, of course, an opportunity – as ever when a Bill is in the Lords – for Ministers to listen to the warnings and advice, especially in relation to modern slavery, child safeguarding, safe and legal routes of passage, and crime enforcement against the gangs.
"And the speakers list for Second Reading suggests judicial oversight, international law, and the lack of an impact assessment are also set to be key pinch points.”
A huge 87 peers have put themselves down to speak at the debate.
They will also debate Lord Paddick's call for the bill to be blocked - but are unlikely to back it as the Government could re-introduce it later this year and push it through with less scrutiny.
The Government plans are expected to be put in front of committees, which will pick through the detail and raise concerns before the bill gets its third reading.
Lord Paddick says the legislation should be thrown out because it "undermines the UK’s tradition of providing sanctuary to refugees by removing their legal right to claim asylum".
He also objects to the withdrawal of protection for modern slavery victims.
His motion to scupper the bill also says it offers no safe and legal routes for refugees, and fails to tackle the backlog of asylum cases.
Green Party peers have said they intend to vote to kill the bill.
Baroness Jenny Jones said: “This Bill is illegal because it breaks international law and should be opposed for that reason alone. It is also immoral and plain nasty.
"It effectively makes all asylum seekers criminals unless they are from a few select countries where the UK has approved pathways and safe routes for immigration such as Hong Kong.”
And fellow Green peer Natalie Bennett said: "This unilateral, illegal, bill can only reduce the chances of working with our neighbours for a fair, just, workable system."
There will also be opposition to the bill from peers furious over demands to ignore human rights court rulings.
Lord Thomas of Cwmgiedd - who served as head of the judiciary in England and Wales between 2013 and 2017 - said: "I think it is a very serious step for the Government to be contemplating putting into force."
But he said such a measure could be defeated when it goes in front of the House of Lords, saying: "Many people would say having the power to ignore a court order is something - unless the circumstances were quite extraordinary - this is a step a government should never take because it is symbolic of a breach of the rule of law."
