Liz Truss has been warned of a major rebellion over plans for a bill that could revoke parts of the Northern Ireland protocol, amid fresh concern in Washington over the UK’s approach. European Union insiders have warned that the British government’s threat to abandon parts of the Northern Ireland protocol risks undermining the international alliance against Vladimir Putin. Officials in Brussels were “flabbergasted” at the timing of an intervention from the UK foreign secretary, who issued a statement on Tuesday night saying she would “not shy away” from taking unilateral action on the protocol. The bill, which is expected to be discussed by cabinet ministers on Thursday, could be revealed next Tuesday. According to a report in the Times the attorney general, Suella Braverman, has approved the plans to scrap swathes of the protocol – a move which would grant Boris Johnson a legal green light to move ahead. In her submission, Braverman reportedly cited the Good Friday agreement as having a greater significance than the protocol, but says that it is being undermined by the trade barrier in the Irish Sea and rising civil unrest. Doubling down on Truss’s remarks, Michael Gove warned the EU that “no option is off the table”, after the UK argued the solution put forward by Brussels last October would worsen food shortages. Between 30 and 50 Conservative MPs canvassed by colleagues said they had significant doubts about whether they could vote for a bill that would unpick an international treaty. Most dismissed the prospect of the bill’s success and described it as a negotiating tactic. Senior MPs warned there were a number of ministers prepared to resign if faced with passing the bill into law. Sources close to Truss have stressed that no final decision has been made and that any potential legislation is intended to run in parallel with further talks. The Northern Ireland minister Conor Burns, styled under a new title of special representative to the US on the NI protocol, was dispatched to Washington this week to speak to senior US figures about the negotiations. They were reported to have been blindsided by the leak of the proposed bill to the Times earlier this week. Burns arrived in Boston on Monday before travelling to DC for meetings with the Department of State and the senior director at the National Security Council, Amanda Sloat, as well as some senators and representatives from the influential Friends of Ireland group. One source described Burns as being keen to point out his close friendship with Johnson. A White House spokesperson said: “We recognise that there have been challenges over the implementation of the Northern Ireland protocol and that talks continue between the UK and EU to resolve these issues. “President Biden has long made clear his strong support for the Belfast/Good Friday agreement. We underscore our continued support for a secure and prosperous Northern Ireland in which all communities have a voice and enjoy the gains of the hard-won peace.” In Westminster, MPs said there was already a strong opposition forming against the principle of the bill, but said most were prepared to stomach difficult negotiating tactics. But they said they expected senior voices to speak out if it went ahead, including one ex-minister who said the former prime minister Theresa May would go further than she had over the internal markets bill which had provoked a number of resignations but was pulled last year. May made a stern intervention on the plans in the House of Commons and MPs described her comments as “opening fire” for more widespread Tory concern. Tobias Ellwood, chair of the defence select committee, said there was widespread concern about the proposed legislation. “Abandoning the protocol is self-defeating. It plays into Sinn Féin’s narrative that a united, peaceful Ireland is better for Northern Ireland,” he told the Guardian. “Binning the protocol will provoke a trade war with the EU at a time when the UK has done so well in leading the European response to Russia’s invasion of Ukraine. It will mean fewer movements of goods and higher inflation.” Most MPs said they would wait to see how much the proposed bill was a device to reignite negotiations. Another MP said there was “huge difference between making preparatory steps as a negotiating tactic which some would understand – and going as far as to whip colleagues to break from an international treaty”. A third said: “As long as it’s posturing, it’s tolerable. If they go through with breaking the protocol, there will be opposition.” Another former minister said they believed Rishi Sunak, the chancellor, had significant concerns about escalatory action by the EU – which has said it could suspend the free trade agreement. “The last thing the Treasury needs is that pressure on supply chains.” EU leaders have also voiced alarm. Simon Coveney, the Irish foreign affairs minister, said Truss’s briefing to the press had gone down “really badly” in Europe, warning that unilateral action would potentially plunge the UK into a trade war with the EU. The EU had been expecting UK ministers to ramp up their approach after the public comments from Johnson and Brexit opportunities minister Jacob Rees-Mogg about bringing forward “reforms”. Broadly, the threats were seen as sabre-rattling designed to achieve leverage for the UK side ahead of the resumption of talks between Truss and the EU’s Maroš Šefčovič. But relations deteriorated on Wednesday, with Coveney saying the “partnership” that has kept Northern Ireland stable is “absent at the moment”. Speaking on a visit to Sweden, Johnson told BBC News there was no need for major EU retaliation. His spokesperson declined to say if the government had modelled the potential economic cost of a trade war. Talks between the UK and the EU about the protocol are about to resume following a pause for the Northern Ireland elections. If the UK abandoned the protocol, the EU could take legal action and restart previous litigation against the UK that the European Commission paused last July, as well as potentially imposing tariffs on British goods or even suspending the EU-UK free-trade agreement.