Conservative anger over same-sex marriage plans will not prevent the Government pushing ahead with legislation, Culture Secretary Maria Miller said.
In a staunch defence of the plans ahead of today's Commons vote which has split the ranks, she said it was in line with the party’s “progressive” past on issues such as slavery.
At least 100 Tory MPs are expected to vote against the Marriage (Same Sex Couples) Bill at its first Commons hurdle today.
The proposals – championed by David Cameron – should pass easily, as they are backed by the vast majority of Labour and Liberal Democrat MPs.
All three major parties have allowed a free “conscience” vote on the issue.
Conservative divisions were further laid bare yesterday by more than 50 senior activists issuing a letter supporting the reform and warning opponents risked “alienating” voters.
It came in retort to a letter delivered to Downing Street on Sunday by more than 20 serving and former constituency chairmen, urging the proposals be delayed until after 2015.
In an interview Mrs Miller said it was “very important” to respect individuals’ beliefs and that there was “absolutely no pressure” on Conservative MPs to vote with the Government.
But she added: “What I will not be doing is stopping the legislation moving forward.
“It’s important we have a fair approach to marriage. Simply being gay is not a good enough reason not to have that available.”
She went on: “Conservative governments have done things for generations which are progressive, all the way back to the position the party had on the slave trade. I think it is a natural progression for marriage, something that has evolved over centuries anyway.”
Justice Secretary Chris Grayling also spoke out in favour – telling gay magazine Attitude it was a “sensible next step” in tackling homophobia in the UK.
“Changing a law has never automatically changed someone’s opinion or belief, but a change in law can result in a more supportive and protective environment,” he wrote.
Mr Grayling said social acceptance of homosexuality over the past two or three generations had been “a real step forward”.
“The Government’s proposals on the recognition of gay marriage are a sensible next step in that evolution. They make it clear that the attitudes of today’s generations are very different to those of the past.
“Of course we need to protect the right of the individual to have a conscience and of religious institutions to follow their own path. But that does not mean that the state has to do the same.”
The Conservative Party’s most senior volunteer, Paul Swaddle, president of the National Convention, was one of more than 50 senior figures who signed the letter backing the reforms.
“By opposing gay marriage outright, we risk alienating the voters we will need in 2015,” it said.
“To win, the Conservative Party must mount a broad appeal. We urge our MPs to listen to the wider views of their electorate as they decide how to vote.”
It came as Liberal Democrat MP John Pugh broke ranks and declared that he intended to vote against gay marriage, insisting there was a “good liberal case” against the move.
In an open letter to constituents, he said his fundamental objection was that the legislation “achieves none of its objectives and weakens the link between marriage and the family”.
“It is my view that the benefits of the gay marriage proposal over and above civil partnership legislation are marginal and the risks considerable,” the Roman Catholic said.
“It draws government (the state) into a whole new series of debatable judgments and rulings on sexual, personal and religious behaviour.
“Far from being permissive in effect, it could herald the advent of ever more arbitrary prescription as we forget why the state legislates at all in this deeply personal aspect of life.”
Labour leader Ed Miliband said he would “proudly” vote in favour and would actively urge his MPs to join him in making “an important step forward in the fight for equality in Britain”.