Shadow chancellor Alan Johnson has admitted his U-turn on graduate tax smacked of "inconsistency".
MPs voted this week to allow England universities to raise tuition fees to £9,000 a year from 2012.
Labour has supported a graduate tax as an alternative policy.
Mr Johnson said there was a "strong case" for such a levy, despite previously saying such a policy would be "very difficult to implement".
Mr Johnson's shift brought him in line with Labour leader Ed Miliband but the government has accused him of "flip-flopping".
Mr Johnson told BBC Radio 4's Today programme: "A graduate tax is now very much back on the agenda in my book."
He pointed out Chancellor George Osborne, Prime Minister David Cameron and Business Secretary Vince Cable had all voted against introducing tuition fees in 2004.
Mr Johnson said: "If you are talking about inconsistency, Osborne, Cameron, Cable all voted against any graduate contribution whatsoever.
"But they are Premier League inconsistency. Mine's Champions League inconsistency."
Mr Johnson's office later made it clear that he meant to use the term "Championship" instead of "Champions League" - which is the level above Premier League for English football teams.
He claimed the coalition's actions had altered the situation and made a graduate tax more attractive.
Mr Johnson said Labour's tuition fee system had been successful because it was a "reasonable contribution" which "enhanced" universities.
But he added: "Since then we have seen the Browne review, and we have seen the withdrawal of 80% of funding and the entire state funding for our humanities and social sciences.
"That puts us in a completely different position."
Thousands protested outside Parliament on Thursday as MPs voted to go ahead with coalition plans to let universities raise fees before violence erupted.
President of the National Union of Students Aaron Porter said students were "incredibly disappointed and angry".
"We've taken to the streets in our thousands, won the arguments and the battle for public opinion. We have lost in the House of Commons only because MPs have broken their promises," he said.
Mr Cable said: "My colleagues accepted, however they voted, that I and my colleagues in the government, we acted responsibly, that we had protected universities and maintained them as viable and strong institutions and produced a policy towards future graduates which is fairer and more progressive than the system we inherited."