Theresa May insisted leadership-backed proposals for an in/out European Union (EU) referendum could be jeopardised by a backbench Tory MP's attempts to force a vote before the general election.
The Home Secretary followed Number 10 in slapping down Adam Afriyie's plan to table an amendment to legislation, which paves the way for a promised vote in 2017.
She said she thought Mr Afriyie had "got it wrong" and added it could pose a threat to James Wharton's Government-backed private members' bill.
Mr Wharton's proposal aims for a referendum in 2017 to give the UK time to renegotiate the terms of its EU membership.
Ms May told BBC1's the Andrew Marr Show: "I think what is crucial is that we have at the next election a Conservative Party that will be offering people a renegotiation, a new settlement with Europe, looking to the future and then putting that to the British people in an in or out referendum.
"What the amendment possibly could do, as James Wharton himself who put in the referendum bill through Parliament has said, is it could actually jeopardise that bill."
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