Croydon North MP Steve Reed joined councillors, health service employees and residents outside Croydon University Hospital to campaign against the accident and emergency and maternity services being under threat.
The Labour MP launched a petition at street stalls in Thornton Heath and outside the hospital over the weekend, because the closing of the services at the hospital, are still a possible option under the Better Services Better Value (BSBV) healthcare review.
Under the preferred options from BSBV, Croydon University Hospital will keep their emergency and maternity services and remain a major acute hospital.
The most preferred option would see Epsom and St Helier Hospital downgraded, whereas Croydon being downgraded is the review's least preferred option.
But in June, BSBV announced the decisions on the proposals had been delayed until after the summer, after NHS England raised serious concerns about its financial viability.
Mr Reed said: "It is simply unacceptable a borough the size of Croydon could be left without an A&E service and it beggars belief that the Tories could even consider forcing parents of new-born children to travel miles further away for the maternity services they depend on.
"We have found real anger on the streets as people realise the Tories are eying up vital local health services for cuts and closure."
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