MPs have voted to split the Isle of Wight under controversial plans to change constituency boundaries.
Electoral reform plans suggest creating constituencies of 75,000 voters but the island currently has 110,000.
Island Tory MP Andrew Turner fears the extra 35,000 constituents could be added to a constituency in Hampshire.
A bid to give special consideration to the island was defeated in the House of Commons by a majority of 81 MPs on Monday night.
In the proposals, Deputy Prime Minister Nick Clegg said, if approved, the changes would reduce the number of MPs by 50, to 600, which could save taxpayers up to £12m a year in salaries, pensions and allowances.
He said the only areas not affected would be Orkney and Shetland and the Western Isles, which were considered "uniquely placed".
If the plans are passed, the Boundary Commission will have to implement the changes by 2013.
Island MP Mr Turner handed a petition to Downing Street in September containing the signatures of more than 16,000 islanders opposed to the moves.
He said: "I admit I am disappointed with this setback but we are not yet defeated and I will fight on - as I promised in my election address.
"Major constitutional changes should not be made by diktat of the deputy prime minister."
The bill now goes to the House of Lords where it could still be overturned.