Britain's Justice Secretary Robert Buckland told the BBC on Sunday that the legislation was a "break the glass in emergency provision", if needed, and that he would resign if he believed the rule of law was broken in an "unacceptable" way.
However, some senior Tories have argued the legislation breaches worldwide law - something the government has conceded - and hence threatens Britain's reputation in the world.
Potential opt-outs from the HRA are now being examined by Number 10, the Ministry of Justice, the Home office and the Ministry of Defence.
A more plausible scenario would be one where the House of Lords would "amend and improve legislation".
"If existing agreements that aren't even a year old are being legislated against in Westminster".
Sir Keir Starmer accused Mr Johnson of having "reigniting old rows" by working to flout his own Withdrawal Agreement, but pledged Labour support if he addresses "substantial" concerns.
In a video conference with his lawmakers, Johnson explained the reason for the bill which he said would protect Britain's economic and political integrity, according to two of those who were on the call.
Mr Gove joined the Prime Minister in urging support for the Bill ahead of a Commons debate on Monday.
Adding fuel to the fire, the Sunday Telegraph reported that British ministers were considering opt-outs from major portions of European human rights law after Brexit, in part to give them greater freedom of action against illegal migrants.
"What they are doing is seeking to obtain that trade deal, but then planning for what happens if we don't get the trade deal". But this way of negotiating, with reason cast aside and cavalier bombast posing as serious diplomacy, is irresponsible, wrong in principle and risky in practice.
Major and Blair, who led Britain through historic peace talks for Northern Ireland in the 1990s, urged MPs to reject the legislation, saying it imperilled the peace process, European Union trade talks and Britain's integrity with the rest of the world. It questions the very integrity of our nation'.
Sir Keir called on Mr Johnson to throw out clauses that could breach worldwide law and those that lead the devolved administrations to warn of a "power grab" to get Labour support.
The veteran DUP politician said "the Internal Market Bill as published is not the finished product but it is massive step forward for business in Northern Ireland".
Despite Mr Johnson's attempts to drum up support, Tory rebels suggested their numbers were growing and opinions were only hardened by Mr Johnson's increased rhetoric.
"Already this Bill is damaging brand United Kingdom, diminishing our role-model status as defender of global standards".
Meanwhile, a local Senator says there's a real fear along the border over the British Government's plans to change the Brexit Withdrawal Agreement.
Theresa May, the predecessor of current Prime Minister Boris Johnson, has also questioned whether worldwide partners would be able to trust Britain in future.
Johnson's contention that the European Union is plotting to choke off food supplies with destabilising new trade barriers between Britain and Northern Ireland is "simply not the case", Irish Justice Minister Helen McEntee told Sky News.
Although the government has refused to retract modifications to the Irish protocol, it is likely that this was an act of brinkmanship on the part of Mr. Johnson.