More than half the Conservatives in the House of Lords are planning to vote against the same-sex marriage bill alongside “dozens” of Labour and Liberal Democrat peers, according to the Telegraph.

A Tory whip told the paper: “I expect more than half of Conservative whips will vote against. I think many of the old guard of Labour peers will do the same. Liberal Democrats peers may also do so and who knows what we will see with the cross-benchers.

“It would have been better for Mr Cameron if he had tried to push this through a year or two ago – before Lords’ developed a taste for rebelling,” the source added.

On 5 February MPs voted 400 to 175 in supporting the government’s Marriage (Same Sex Couples) Bill – a majority of 225 votes – following an afternoon of heated debate in the House of Commons. The bill will now go to a Commons committee, and is set to be voted on by the House of Lords in May.

Conservative peer Lord Lawson of Blaby plans to vote against the bill, as he feels it will not further the anti-discrimination movement started by the introduction of civil partnerships.

He said: “Discrimination did exist before but it was ended by the introduction of civil partnerships. I was perfectly happy with that, but what we have now is a question of the redefinition of marriage. I do not believe the case for that has been made.”

Another Conservative peer said: “The prime minister has just decided on a whim that this is necessary. He apparently thinks I have no idea what is going on in the country… I think I have a hell of a lot more of an idea that is going on in the country than he does.

“The public were assured by the Labour government that civil partnerships would not slip into gay marriage. But there you are: don’t put your faith in politicians.”

Lib Dem peer Lord Tyler said he predicted that the “backwoodsmen” – peers who rarely attend votes – would come out in force to filibuster the bill, delaying it through a barrage of proposed amendments.

Similar filibustering tactics have been used by anti-equal marriage MPs in the French parliamentary debate, with 5,396 amendments filed. MP Jerome Guedj, who was caught playing Scrabble during the debate last week, said he had been trying to pass time while listening to “thousands of identical amendments, each of which takes five to ten minutes to process.”

British Labour peer Lord Stoddart called the bill “completely unnecessary” and predicted that there would be a large number of amendments filed by Labour peers in attempts to “help to modify, if not destroy, the bill”.

Lord Stoddart said: “Marriage was devised a long time ago to protect women and children – to tie the male to the family so that the children could be brought up and protected by two loving parents. That does not really apply in the case of homosexuals.

“I am sure that there will be many amendments and it is possible that the House of Lords will throw it out. To get this through by the end of the year is very unlikely,” he added.

If his predictions are correct, Labour opposition would prove embarrassing for party leader Ed Miliband, who celebrated the passing of the bill in the Commons last week.

Conservative peers alleged to be planning to vote against the bill include Lord Waddington, Baron Cormack, Lord Mackay, and Baroness O’Cathain. Labour Lord Brennan, Lord Carey, the former archbishop of Canterbury, and the crossbenchers Lord Curry, Lord Tombs and Lord Singh are also expected to oppose the bill.

One Conservative peer who plans to vote for the bill is Lord Deben. He argued that it was hypocritical of Tory peers to oppose the bill, as it upheld both the importance of marriage and the importance of personal freedom.

“If you believe in fidelity and permanence it seems an odd thing not to encourage people to celebrate that,” he said.

“Science has taught us that some people have this attraction and don’t have heterosexual attraction. This is now universally agreed and so it is the right thing to do for society to acknowledge that.”

He added: “I find it very difficult to listen to the inconsistency of people who themselves have been several times married now standing up in the House of Commons and defending the sanctity of marriage.”