Conservative Equalities Minister Helen Grant says the government will not be offering tax breaks to married and civil partnered couples in next month’s Budget.

Prime Minister David Cameron and Chancellor George Osborne have been under mounting pressure from disgruntled Tory backbenchers to provide the measure – in order to placate ill feelings over the Marriage (Same Sex Couples) Bill.

MPs will vote on the bill at 7pm today – reports suggest upwards of 120 Conservative MPs could vote against the government’s plans, including some cabinet ministers.

The Conservative Party promised a tax break on married and civil partnered couples at the last election but coalition partners the Liberal Democrats oppose the move.

On Tuesday, Helen Grant, the minister for women and equalities, confirmed that next month’s Budget would not contain a new tax allowance for married couples.

Asked on Pienaar’s Politics on BBC Radio 5 Live if the tax break was “off the table” for the forthcoming Budget, she said: “Yes it is, for now, but I’m sure it will be something that will arise in the future and will be looked at and considered very carefully.”

Mrs Grant will be part of the Department for Culture, Media and Sport (DCMS) team pushing the Marriage (Same Sex Couples) Bill through the House of Commons later today.

Last week, she told the House Magazine that the bill was a “wonderful opportunity” and that it complemented her Christian beliefs.