Andy Burnham said the unbearable suffering in Gaza was a cause of "huge hurt", and on the day he submitted his bid to become Labour's next prime minister pledged his government would do better. “I know many people feel that at the start of Israel’s military action in Gaza my party didn’t get it right and I am sorry about that. The response has too often not been good enough. We need to do better,” he said. “We’ve got to do more to put pressure on the Israeli government. "Let’s be honest, the UK was too slow to call for a ceasefire. And we must now do more to strengthen our approach.”Mr Burnham accused Israel of making a two-state solution impossible and said he would do everything he could to ensure the Israeli government adheres to international law. He ensured he would be the only candidate for the prime minister's job by securing the backing of 322 MPs on Thursday. He is expected to replace Keir Starmer as prime minister as soon as Monday, July 20.Foreign Secretary Yvette Cooper told the Chatham House London Conference on Thursday that the government could move on two issues very soon. Speaking after Mr Burnham's message, she said he recognised the need to challenge what was happening in Gaza."We're looking at to try and go further around the sanctions regime and also looking at the issues around trade with illegal settlements," she said. "Ultimately, both are issues that Andy will need to set out himself and say what he wants to take forward."Change imminentThe former Manchester mayor, who resigned from the position so he could stand in a by-election in Makerfield to return to Parliament, twice stood for the leadership when he was previously an MP. He came fourth in 2010 when Ed Miliband was elected, and second to Jeremy Corbyn in 2015.“It's a strange thing to say, but I’ve just been to nominate myself to be leader of the Labour Party," Mr Burnham said in a video clip filmed in parliament.“The nomination process has opened this morning. So glad to see some MPs going in. I’m still the only candidate in the race.“But the thing will go on over the next few days. So it won’t be the final word. But, yeah, it’s all starting to feel very real.”A list of MPs who have signed up to support Mr Burnham was expected to be published on Thursday evening. He needs 81 nominations to be able to stand before the deadline next Wednesday. The winner would be announced on Friday, July 17, before being given the keys to No 10 Downing Street the following Monday.Other possible candidates, such as Wes Streeting and Al Carns, have already chosen to stand aside. MPs who may have been considered potential candidates have been jockeying to be named in Mr Burnham’s cabinet.Meanwhile Mr Starmer has been making his swansong trip as Britain’s Prime Minister to the Nato summit in Turkey this week as he tries to cement his legacy.Mr Burnham’s pitch for leadership has centred on domestic issues, even as the US-Iran war heats up again, the Ukraine-Russia conflict grinds on and American President Donald Trump continues to disrupt the global order.Mr Burnham on Thursday made his first big intervention on foreign policy, writing a piece for The Times newspaper in which he vowed to rebuild Britain’s “hard power” and reduce dependence on other countries for defence equipment, while strengthening ties with allies.He said Britain needed to deal with “a new era that is very different to the one in which much of our current military equipment was first designed”.“We will do this by boosting our sovereign capabilities in areas where we already have incredible strengths and in the tech of the future – from shipbuilding and energetics to AI and quantum,” he wrote. “Re-industrialisation through defence – and other sectors – is critical for both our economic and national security, building resilience in all our places. It will be a core priority for me.”Mr Burnham said he intends to keep Jonathan Powell in place as National Security Adviser.He also promised to stay firm on Britain’s commitment to Nato, the UK’s nuclear deterrent and its “critical” defence and security relationship with the US. The country’s support for Ukraine “will not waver", he added.He said the global picture was darkening and “we must take concerted action to enhance our resilience, starting at the local level”. Mr Burnham said the closure of the Strait of Hormuz had “raised the cost of filling up the family car”, while the war in Ukraine pushed up food bills and energy prices. “State-backed cyber attacks on our hospitals have disrupted critical care and patient safety. When hackers brought Jaguar Land Rover to a standstill, it was workers in the Midlands who paid the price, with thousands of jobs at risk and nearly £2 billion wiped from our economy," he said. But Britain is not powerless in the face of these threats, he said.Despite limited scrutiny of what Mr Burnham will do when he becomes prime minister, MPs have been publicly showing their support for him. Diana Johnson wrote on X that: “Andy will work to honour manifesto pledges and build on the progress made since 2024 in areas like child poverty, boosting defence spending and controlling immigration."Tom Hayes said he would be “proud” to nominate Mr Burnham, saying he had “hope in our politics and power with the people who know their places best. Industry back in our heartlands and the acceptance, finally, that Britain can make things”.Andy McDonald wrote: "I was delighted to be one of the very first Labour MPs to nominate Andy Burnham for leader this morning. There was quite a queue.”