Home Secretary Theresa May has vowed to reverse the shock rejection of directly-elected police commissioners by the House of Lords.
Mrs May said the "great majority" of Liberal Democrat peers had voted with the coalition and blamed the result on "sheer opportunism" from Labour.
Thirteen Lib Dem peers joined forces with Labour last week to help strip the creation of directly-elected police commissioners from the flagship Police and Social Responsibility Bill.
Mrs May told BBC One's Andrew Marr Show: "The great majority of Liberal Democrat peers voted with the Government.
"The Deputy Prime Minister (Nick Clegg) said the other day that the decision to have directly-elected individuals, with the appropriate checks and balances from what we're calling the police and crime panels, is a coalition agreement."
She added: "The Labour Party has supported an element of direct election in terms of the oversight of the police. It was sheer opportunism from Labour peers in the House of Lords that went against Labour party policy."
The Home Secretary said the Government would "of course listen" to the ongoing debate in the Lords during the Bill's committee stage.
"But I expect we will bring it back to the Commons and we will reverse the decision in the Commons because this is a coalition agreement," she added.
Police and crime commissioners were due to be elected from May next year to replace police authorities in England and Wales.
They would have the power to hire and fire chief constables and would set the police force's budget and "strategic direction".
Mr Clegg had indicated his support for his peers' efforts to slow the introduction of elected commissioners by piloting the scheme - but the upper house went much further.
Peers supported an amendment tabled by Lib Dem Baroness Harris of Richmond stating that the commissioners should be appointed by a local police and crime panel, rather than be directly elected.
Mr Clegg later pledged to overturn the vote in the Commons, saying: "It is a coalition agreement commitment and I take very seriously, even in cases which don't, as I say, flow from one side of the coalition, our collective duty to honour what we've said we were going to do in the coalition agreement."