Cross-party discussions have been launched to block David Cameron's bid to scrap the Human Rights Act, with potential rebels in his own party being targeted to vote against its abolition.
Details of the operation were revealed as senior Tories, including a government minister who would be forced to resign in order to oppose the move, indicated their concerns about the plan.
The SNP, which is now the third biggest party in Parliament, has begun sounding out lawyers on the Tory benches about uniting to defeat Cameron's plan to replace the Act with a British Bill of Rights.
The government will set out its legislative programme in the Queen's Speech this week, and SNP home affairs spokeswoman Joanna Cherry - a QC - said she had begun work on sounding out potential rebels.
She told Sky News that scrapping the act would be a "very retrograde step".
"The SNP would be happy and proud to lead the opposition to repeal the Human Rights Act in the House of Commons. We are already aware that a number of leading Tory backbenchers will be with us on that," she said.
The Sunday Telegraph quoted an unnamed minister as saying they "will probably oppose it", adding: "The idea that my constituents should have fewer protections available as a last resort is not something that I can accept."
Labour and the Liberal Democrats are also expected to oppose attempts to repeal the Act and, as Cameron's majority is just 12, any rebellion will leave him vulnerable to defeat.
Cherry, who declined to give an estimate of the number of potential rebels, said: "We are very confident that we can lead a progressive consensus in the House of Commons which would be sufficient to defeat the Government, drawing on our contact with Tory backbenchers."
She added: "There are some informal channels. I myself am from a legal background, before I became an MP I was a QC at the Scottish bar. I am on friendly terms with some of the lawyers in the Conservative Party, I will be speaking to them informally, as will some of my colleagues to see if they will be willing to vote with us on this."
In the Sunday Telegraph, former chief whip Andrew Mitchell said he was "extremely sceptical" about the proposals.
"I am very concerned about withdrawing from the European Court of Human Rights," Mitchell told the paper.
"I have clear views about the importance of international justice, which we need to expand, and Britain pulling out of the European Court will send all the wrong signals on the British commitment to expanding human rights around the world."
The Human Rights Act incorporates into UK law the rights and liberties enshrined in the European Convention on Human Rights, but has been blamed for a series of controversial judgments.
Former attorney general Dominic Grieve, who has already aired his concerns about Cameron's plans, said replacing the Act with a British Bill of Rights was "not in itself a foolish idea" but warned against going further and withdrawing from the European Convention.
"A Bill of Rights that places us outside the European Convention on Human Rights would be reputationally disastrous for this country and would have very serious consequences for the survival of the Convention," he said.
In a further sign of the SNP's willingness to disrupt efforts to scrap the Act, the Scottish Government's Cabinet Secretary for Social Justice, Communities and Pensioners' Rights, Alex Neil, has already written to Justice Secretary Michael Gove "to reiterate the Scottish Government's opposition to the repeal of the Human Rights Act".
SNP leader and First Minister Nicola Sturgeon raised the matter directly with the Prime Minister when they met and indicated Holyrood could refuse consent to abolish the Act.
The First Minister claimed the Conservatives' agenda "lacks legitimacy in Scotland", where Cameron's party has just a single MP and the SNP holds 56 of 59 seats.
She said: "SNP MPs will work across party lines at Westminster to defeat the Tory government on the Human Rights Act - and the SNP Government will invite the Scottish Parliament to refuse legislative consent to scrap it, given the strong devolved dimension.
"This important issue illustrates how Holyrood working together with SNP MPs and others at Westminster can challenge a Tory agenda that lacks legitimacy in Scotland - and help the cause of progressive politics across the UK."
Shami Chakrabarti, director of civil liberties campaigning group Liberty, said: "The Human Rights Act was passed with cross-party support and allows British judges to give effect to Churchill's post-war legacy.
"Liberty is proud to see politicians from across the spectrum and kingdom uniting in defence of democratic values. It will be a hard fight but it's one we have to win."