Rightwing Conservative MPs have called the government’s Rwanda immigration bill “partial and incomplete”, and urged Downing Street to agree to amend it before a crunch vote on Tuesday night. A panel of two MPs and two lawyers convened by the European Research Group (ERG) of backbench Tories published its analysis on Monday saying the bill would not stop asylum seekers successfully appealing against being deported to Rwanda. The analysis clashed with the government’s own legal advice, which ministers published on Monday in an unusual move highlighting how high the stakes are for Tuesday’s vote. Mark Francois, the chair of the ERG, said on Monday: “The bill provides a partial and incomplete solution to the problem of legal challenges in the UK courts being used as stratagems to delay or defer the removal of illegal migrants to Rwanda.” He added that he believed the bill should be withdrawn entirely to give the government time to amend it. “Rather than plough on regardless, [the government] would be better to pull the bill and to come back with a better draft that doesn’t have all these holes in it.” The analysis commissioned by his group said: “We do not believe that it goes far enough to deliver the policy as intended. “Resolving, comprehensively, the issues raised by this analysis would require very significant amendments, some of which would potentially be outside the current title’s scope, and the bill would look very different.” However, the government’s legal advice disagreed with this conclusion, saying: “The government’s approach is tough but fair and lawful … it has a justification in the UK’s constitution and domestic law, and it seeks to uphold our international obligations.” Downing Street has launched a last-minute lobbying operation to try to persuade Tory MPs to back the bill at its second reading on Tuesday night. The bill was published last week in an attempt to tackle the concerns raised last month by the supreme court, which ruled the entire policy was unlawful. It is designed to work alongside a new treaty with Kigali that aims to better protect the safety of asylum seekers who are sent there. The bill would empower ministers to ignore temporary injunctions raised by the European court of human rights that can stop migrant flights taking off at the last minute. But it does not set aside the European convention on human rights entirely, and would allow individuals to launch legal appeals to argue they should be spared deportation because of individual circumstances. The analysis by the ERG said: “Experience to date in cases about attempted removal of illegal migrants to Rwanda demonstrated that individual challenges are likely to be numerous, and that they have had a high rate of success.” But in its competing analysis the government argued: “Not to [allow individual challenges] would mean ministers accepting that those unfit to fly, for example those in the late stages of pregnancy, or sufferers of very rare medical conditions that could not be cared for in Rwanda, could be removed with no right to judicial scrutiny.” With Labour planning to vote against the bill, it would require 56 Conservatives to abstain, or 28 to vote against it, or a mixture of both, to defeat it outright. Sunak said last week he did not consider the vote to be a de-facto vote of confidence in his own leadership. However, many senior Conservatives say they do not believe he would be able to suffer a defeat on such an important piece of legislation without immediately calling a vote of no confidence in himself. Members of the “five families” of Tory backbenchers met on Monday afternoon and are due to meet again in the evening, and once more on Tuesday, as they decide whether or not to vote for the bill on Tuesday night. Some rightwing MPs said they expected to vote for the bill at this stage and then try to amend it later, but added they were unlikely to make a final decision before the meeting on Tuesday. One member of the centrist One Nation group said they would also vote for the bill and then focus their efforts on preventing any rightwing amendments. “What’s the alternative?” the MP said. “At my end of the market we will almost certainly back it, with misgivings.”