A group of MPs are urging David Cameron to keep his commitment to introducing a tax break for married couples.
In a letter to The Telegraph, fifteen Conservatives, including former ministers, demanded action as part of the Finance Bill 2013.
The Tory party promised a transferrable tax allowance for married couples in their manifesto, and these MPs are concerned plans will be dropped as we are now past the half way point of this Parliament.
Meanwhile, the Government is pressing ahead with plans to redefine marriage, despite this never being pledged.
The letter said the MPs believe the proposed tax break is “a vital weapon in combating child poverty”, citing research in America which showed that college graduates who become single parents are likely to be poorer than those who only complete secondary education, but go on to marry.
Those who signed the letter include former defence minister Sir Gerald Howarth, and former children’s minister Tim Loughton.
The tax allowance could save four million couples £150 a year, when one spouse stays at home.
Chancellor George Osborne made no mention on Tuesday of tax breaks for married couples when he outlined the social agenda he said would win the election for the Conservatives.
He claimed that allowing same-sex couples to marry is a key part of an election-winning strategy.
Cabinet minister Ken Clarke recently backtracked on comments he made where he denied the party ever made a marriage tax pledge.
Work and Pensions Secretary Iain Duncan Smith has also urged the Government to bring in the changes as soon as possible.