Education minister David Laws has said today that it would have "technically possible" to keep the tuition fees pledge but only if the Liberal Democrats had been governing on their own, after the Deputy Prime Minister issued an apology over the pledge.
Mr Laws told BBC Radio 4's Today programme that if the party had "ditched other key commitments" such as tax breaks for the low paid and support for disadvantaged pupils, then it would have been "possible".
He added that all Lib Dems bore a "collective responsibility" but denied it was a failure of leadership on Nick Clegg's part, pointing out that the party had to keep its pledges on a range of other "big and important issues".
Labour Deputy Party Leader Harriet Harman accused Nick Clegg of "crying crocodile tears", after the Deputy Prime Minister issued an apology over pledging to scrap tuition fees.
Ms Harman said in a short statement: "This was not just the small print of his manifesto, this was Nick Clegg's key election promise when he asked people to vote for his party. It is not good enough for him to just brush that promise aside.
"Instead of crying crocodile tears he should vote with Labour to bring these tuition fees down. If Nick Clegg does not back his words with action he is just weak and spineless."
Asked whether the Liberal Democrats would think more carefully about what it pledges in the next general election, Vince Cable said they would "not be going into next election with a lot of expensive pledges".
He also acknowledged the "damage" that breaking the pledge had done to trust in politics.
The Business Secretary Vince Cable has said that he too apologises for the pledge made by his party, the Liberal Democrats, that it would not raise tuition fees. He told the BBC's Newsnight programme that it was a "collective" decision.
He also said there was a distinction between the pledge, and the policy that the party has now adopted, which he said is correct.
The Liberal Democrats should either back or sack their leader Nick Clegg at next week's party conference in Brighton, one of his former advisers has said.
Mr Reeves, who served as director of strategy, said the Deputy Prime Minister could not avoid the question about his future as the party's leader. But the 43-year-old warned the Lib Dems that if they decide to back the Deputy Prime Minister, they must stick with him.
Writing in the New Statesman, Mr Reeves, who has since left the UK to live in the United States with his family, said: "The mutterings have been growing louder for months, certainly since another bruising round of local election results in the spring.
"The question of Clegg's leadership has to be addressed. Indeed, given the party's current position, it would be irresponsible not to do so.
"It is some comfort that David Cameron is facing similar squalls in his own party: at least now the necessary pain of coalition is being shared.
"Cards on the table: I think the party must stick with Clegg, and that Clegg must stick with both liberalism and coalition. Once the party caravan packs up on 26 September and heads inland after conference, the muttering has to stop. If the party is not to sack Nick Clegg then it must back him."