Rishi Sunak’s plan to fly people seeking asylum to Rwanda this spring appears to have been put back to the summer after House of Lords insisted on changes to the scheme. On Thursday the prime minister’s spokesperson said the Lords were responsible for any delay after attaching unwanted amendments to the deportation bill. Pressed on whether spring was still the target, the spokesperson told reporters: “I’m not going to get ahead of the bill passing, which obviously we’ve seen again last night has continued to be held up.” Below, we examine what the impact will be on the scheme and what will happen next. Where does the latest delay leave the Rwanda deportation bill? The bill, with two Lords amendments attached, still has to be voted through both houses before it can be given royal assent after being passed between them three times. In parliamentary jargon, it is stuck in “ping pong”. It will be voted upon by MPs on Monday before moving to the Lords later that day. The government says it will resist pressure to offer a compromise to peers, who want to ensure that it allows an independent committee to decide whether Rwanda is a safe country, and exempts Afghans who helped British troops from deportation to Rwanda. What is ‘ping pong’? The process by which proposed new laws are sent back and forth between the Houses of Parliament – Commons and Lords – if they do not agree on the wording of a bill. A coalition of cross-bench, Tory rebel and opposition peers are refusing to back down over two issues – the rights of Afghans and scrutiny of the treatment of refugees in east Africa. Will the bill pass? The Lords could hold out for more rounds of ping pong – many peers remain furious with the proposed bill. Usually there is some form of compromise or the Lords give way to the elected chamber. But in theory it could continue until “double insistence” takes place – both sides refuse to back down over an amendment – and then the bill is lost. This is extremely rare but not without precedent – it happened to the European Parliamentary Elections Bill 1997–98. Government sources believe the Rwanda bill will go through on Monday. What happens if and when the bill goes through? It will be a minor political triumph which Sunak is expected to grab with both hands. Expect a press conference or a Downing Street lectern. When will planes take off for Rwanda? Home Office sources say that flights are unlikely to take off before late June, more likely July. Why the delays? Asylum seekers are expected to challenge their removal on a case-by-case basis, which could lead to their immediate removal from a flight. The bill allows challenges if a detainee faces a “real, imminent and foreseeable risk of serious irreversible harm if removed to Rwanda”. People suffering serious mental or physical conditions, victims of torture and anyone who is shown to be suicidal could launch a challenge on these grounds. Some delays could be due to the appeals process. Many people subject to removal will have eight days to lodge claims and they will need to present compelling evidence to support their case. Where the Home Office refused the claim without a right to appeal, permission to appeal will need to be obtained within 23 working days. What other issues have been expressed about deportations? Lawyers representing asylum seekers are deeply concerned that there will be a risk of suicide among those told they are being removed to Rwanda. Unions representing border guards have expressed concern that some claimants may resort to attacking their members in order to avoid being deported. The ISU union – which represents frontline Border Force and immigration workers – said its members were concerned about potential physical resistance from people being taken into detention for Rwanda flights, and on the plane itself. Lucy Moreton, an ISU professional officer, said: “Given the undertaking that we will not send anyone with a criminal record to Rwanda, and given the high stakes involved, there is serious concern that migrants may take to assaulting staff as a way to avoid removal.” Any other obstacles before a flight takes off? Ministers have not confirmed if they have secured the planes which can deport large numbers of people. Although the Home Office says there are many options on the table, officials have said they are struggling to confirm airlines willing to facilitate mass deportations. The Times reported on Tuesday that AirTanker, an aviation company that provides a fleet of 14 airbuses to the RAF to fuel and transport the military, is being lined up to take people to Rwanda. AirTanker – whose involvement in talks over the Rwanda plan was revealed by the Guardian – declined to comment.