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."
Adam Afriyie tells ITV News that a referendum in October next year will "strengthen the Prime Minister's hand" in Europe and will settle a remaining constitutional issue ahead of a new government in 2015.
Adam Afriyie told Sky News' Murnaghan that his amendment would strengthen David Cameron's position because European leaders would believe they have to come forward with offers or changes to persuade the British people to stay part of the EU.
Anyone under the age of 56 hasn't had their say on our membership of the European Union. In fact, nobody has had a say on our membership of the European Union because nobody has ever been asked.
What I am saying is we should have that referendum in 2014 and over 50% of the population want that, 80% want the referendum, 80% of businesses as well want the certainty, so I think this is a good thing.
UKIP leader Nigel Farage responded to Adam Afriyie's position on an EU Refurendum in 2014, telling BBC One's Andrew Marr Show that David Cameron's changing stance has left people unsure of what to believe.
"What Adam Afriyie has done is he has put his finger on the real problem and that is, four years ago Mr Cameron gave us a cast-iron guarantee of a referendum.
"This time last year he was saying 'no referendum' and he's now saying there should be a referendum and people aren't quite sure what to believe."
Adam Afriyie's plan to steer leadership-backed legislation on an EU referendum through Parliament has been criticised by fellow Tory MP James Wharton.
Wharton suggested the move would delay and even "kill" the private member's bill he introduced in July, and hoped Afriyie would "rethink" his approach.
He said: "We need to build as broad a base of support for the bill as we can if we are to get it through Parliament and the policy of a renegotiation, followed by an in/out referendum, is the right one to do that and the right one for the country.
"I hope MPs will decline to support it as the ultimate impact might well be to kill my bill, which would only help those who don't want any referendum at all."