Shadow health secretary Andy Burnham has backed the campaign to save St Helier hospital.
Labour MP Mr Burnham has promised to write to doctors urging them to hold public meetings where people's concerns about the future of the threatened hospital can be raised and their questions answered.
He made the promise after meeting Labour party campaigners from the area including prospective MPs Siobhan Tate and Emily Brothers.
Mr Burnham told the campaigners he had secured £219million in funding for the redevelopment of the hospital while he was health secretary under the Labour government and said he was sad those funds have since been redirected to the treasury.
He also said a Labour government would repeal the controversial clause 119, voted through by Parliament in March, which gives ministers greater power to close financially troubled hospitals.
Emily Brothers, parliamentary candidate for Sutton and Cheam, said: "After both Sutton Lib Dem MPs Paul Burstow and Tom Brake ignored thousands of local voices and voted through the Tory-drafted hospital closure clause earlier this month, we knew that the one place local people could turn to for real help was Labour.
"We asked Andy to stand with the people who have signed our petition and contact Sutton and Merton Clinical Commissioning Groups to ask that they engage with the community and campaigners to secure St Helier's future."
Mr Burnham also thanked the campaigners for their efforts to save the hospital.