David Cameron has opened his speech at the Conservative Spring Forum by saying that his party came to power in "perilous" times and that it was "wrestling with historic debts".
He added: "We are here to fight, we are here to win and we have never been more up to the task of turning our country around."
More top news
Transport Secretary Chris Grayling believes Network Rail should share the responsibility with private train operating companies.
Two vehicles were swallowed up by the sinkhole on Sunday night, killing Dora Linda Nishihara and injuring one man.
Elliott Livingstone, aged three, spent most of his life in hospital before the operation in April.