Labour’s Shadow Home Secretary and Shadow Minister for Equalities, Yvette Cooper, has told PinkNews.co.uk that the government needs to remember “who the opponents are” of the same-sex marriage bill in the wake of last week’s row about House of Lords timetabling.

The second reading House of Lords vote of the Marriage (Same Sex Couples) Bill takes place on Tuesday at 6pm – several hours later than originally planned after it became apparent Monday’s debate was unlikely to be concluded until the early hours of the morning.

The prospect of peers not being able to stay the course and support the bill caused Labour to sound the alarm bells last Wednesday, with the party warning a 2am vote could be “very risky”.

But the intervention drew a swift rebuke from an unnamed government source who said: “The government wouldn’t do anything to jeopardise the equal marriage bill and it’s disingenuous to pretend it would. If we need to have the vote in the Lords the next day because second reading is likely to run past peers bedtimes, then that’s fine.”

The source added: “It was the Labour Party and the Liberal Democrats that sought to back bill wreckers with the Civil Partnership amendment in the Commons.”

MP Kate Green, Labour’s Shadow Minister for Equalities, responded by accusing the government of “lashing out at the Labour Party” over the “poor handling of the same-sex marriage bill”.

Speaking exclusively to PinkNews.co.uk, Shadow Home Secretary Yvette Cooper also criticised the unnamed government source’s comments and said she was surprised by the tone.

“Yes I thought that was really odd,” Ms Cooper said, “And I thought it was a really odd thing to say. The only reason that we got the bill through the second reading and that third reading [in the Commons] was on the basis of Labour votes. We did put down the amendments in order to make sure we could get the whole thing through without delay”.

Ms Cooper was referring to the Commons tussle in overcoming Conservative MP Tim Loughton’s potential wrecking amendment to the bill, which called for the introduction of civil partnerships for heterosexuals, a measure outside of the bill’s principle intention.

Overstepping this was done via Labour’s manuscript amendment, which required the support of pro-equal marriage Tory and Liberal Democrat MPs. There has since been political jostling when it comes to taking credit for ‘saving’ the bill at various different stages.

Labour’s Shadow Home Secretary is adamant that her party raised concerns with the government about the potential danger of a late night House of Lords vote weeks ago. She also suggested that the remarks of the government source were likely to have come from within the Conservative side of the coalition.

“I just felt where did this come from?” Ms Cooper said to PinkNews.co.uk. “I understand that they’ve got huge problems within their party and on their own benchers,” before adding: “They have to deal with that. They are not getting on with supporting the bill.”

She continued: “I have also always said I think it is the right thing to do for David Cameron to have brought [the bill] forward even though it has been difficult for his party and even though he has had huge opposition [for] doing so. I think it has been as a result of a lot of the work Labour has done in order to make sure we can get it through and so that’s why I think it is so odd for them to suddenly be, you know, making those statements [and] that we have the unattributed statements over the last week”.

Ms Cooper said to PinkNews.co.uk: “They need to recognise who the opponents are for the bill and to deal with the opponents and with the supporters of the bill and we will keep supporting them to get it through.

Asked on what was likely to happen with this week’s second reading of the Marriage (Same Sex Couples) Bill in the House of Lords, Ms Cooper told PinkNews.co.uk: “Well I think there is a lot of strong support for the bill in the House of Lords… yes there will be some people who oppose it just as they have opposed previous legislation. I think, Labour [in] the Lords are working really hard talking to everybody and campaigning – we hope that it will get a big boost in the Lords”.

When asked if she had personally attempted to change the minds of Labour colleagues who were wary of the bill, Ms Cooper stressed there had always been overwhelming support for the principle of equal marriage in the party and that Labour had come from a “strong starting point”.

In last month’s third reading of the bill former Labour Prime Minister Gordon Brown voted in favour.

However, in the run up to the 2010 general election Mr Brown, told PinkNews.co.uk that he would not support same-sex marriage.

Writing in a readers’ question and answer feature, he said: “At the moment there’s a distinction drawn between civil and religious unions, and when civil partnerships were being introduced they took the same form as a civil union which a heterosexual couple would have. We later made it illegal to discriminate on partnership status – so it is illegal to treat someone in a civil partnership different to a married person.”

At the time, Liberal Democrat leader Nick Clegg told PinkNews.co.uk that he supported same-sex marriage, while David Cameron said he was “open” to introducing marriage equality.

Asked by PinkNews.co.uk to comment on Mr Brown’s 2010 decision, Ms Cooper said: “Well I don’t know what both decisions were. I mean I think it is the right thing to do [to support equal marriage], my strong view is that it is the right thing to do and it is the right thing to do it now,” she added: “It is the next step, it is the right thing to do and I think it’s not the end of the road, we still have a lot more to do [on gay equality].”

Having caused large-scale divisions within the Conservative Party and put Prime Minister David Cameron’s leadership under strain, Yvette Cooper says “it would obviously have been easier” for a Labour administration to have legalised same-sex marriage, but she does not share the view that it was a failure not to have done so under Labour’s previous 13-year term in office.

Ms Cooper believes it is only now possible to introduce the measure because Labour’s previous equality legislation, such as the Civil Partnership Act 2004 and the Equality Act 2010, laid the groundwork for the Marriage (Same Sex Couples) Bill.

“The reason it is possible to do gay marriage now and to do equal marriage now is because we have all of the legislation in the past that built up to it.”

Ms Cooper released a video for the Out4Marriage campaign last year.

Husband and Shadow Chancellor Ed Ball also released a video in support of the Out4Marriage campaign in May 2012.