Villagers will take up the fight against the threat to casualty services at the Princess Royal Hospital this week.
More than 54,000 people signed a petition opposing changes proposed by NHS chiefs - about 7,000 more than estimated when Dame Vera Lynn handed over the forms on Friday.
The health chiefs' most controversial suggestion is to downgrade A&E at the Princess Royal and send urgent cases to Brighton instead.
Lewes MP Norman Baker will speak at a public meeting to discuss the hospital's future on Wednesday.
Members of the Princess Royal Action Group, which raised 37,000 signatures in a petition, will be in the audience at Newick Village Hall.
Mr Baker's constituency includes areas served by the Princess Royal including Wivelsfield Green, Ditchling, Plumpton Green, Newick, and Chailey.
He said: "The overwhelming view of my constituents is that they are against the suggestions, and that there is genuine concern about accessibility of hospitals in Brighton for people needing urgent treatment."
The Argus Save Our A&E petition raised more than 17,000 signatures.
And the Princess Royal Action Group says more than 37,000 people signed its petition.
Campaign organiser Anne Jones, from Burgess Hill, said: "It is phenomenal, that's the word for it.
"The villages would be hard hit by the changes that have been suggested and there is a feeling that they have been left out of the equation."
The petitions will be considered at a future meeting of the Central Sussex Partnership Programme Board.
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