All Liberal Democrat ministers will vote to raise the cap on university tuition fees in England, party leader Nick Clegg has said.
There had been speculation that some might abstain from the vote over the controversial policy.
But Deputy Prime Minister Mr Clegg said ministers were "as one on this" and would vote "as a team" on Thursday.
Energy Secretary Chris Huhne may be forced to return from the UN climate summit in Cancun, Mexico, for the vote.
He has been trying to find a "pair" - an opposition MP to join him in not voting - but Labour has so far declined.
And Julian Lewis has become the second Tory MP to say he will vote against them.
Speaking after addressing his MPs on Tuesday evening, Mr Clegg said: "The ministerial team in government... every single one will vote for this measure because it is the best possible, the fairest possible measure to ensure we have world class universities in future and that youngsters from whatever background can continue to go to university.
"That's why all of us as a team in government will vote for this bill on Thursday."
He said that did not include parliamentary private secretaries - but those with doubts were being encouraged "to take up the opportunity in the coalition agreement to abstain".
It looks like the party will be split three ways over the plans to to raise fees in England to as much as £9,000 a year with some backing, some opposing and some abstaining from the vote.
Before the 2010 election the Lib Dems pledged to phase out university tuition fees over six years.
Lib Dem MPs also signed a pledge organised by the National Union of Students during the election campaign to oppose any future rises in university tuition fees from the current £3,290 a year.
But the policy of the government - in which the Lib Dems are partners - is to support a rise.
'Walk through fire'
At a meeting ahead of Thursday's vote on the proposals, Mr Clegg told his MPs he had hoped they could "walk through the fire" together - but he now accepted a collective position was not possible.
He praised the way Lib Dem MPs had conducted themselves in a "difficult" situation and acknowledged there had been a "lot of pressure" from the media and protesters.
But he said that "to govern was to choose" and, with money tight, the coalition had decided to pump funds into early years education.
Under the terms of the coalition agreement, Lib Dem MPs, including ministers, are allowed to abstain on the issue.
However, former party leaders Charles Kennedy and Sir Menzies Campbell have said they will vote with Labour against the increase.
BBC political editor Nick Robinson said Mr Clegg expected at least half of his 57 MPs to vote for the proposals.
A survey of Lib Dem MPs by the BBC suggests wide divisions on the issue.
All 57 were contacted on Monday to gauge how they planned to vote on Thursday, with 13 saying they would vote with Labour against the fees proposal.
A further 13 said they were undecided, while two said they would back the government. Sixteen refused to say how they would vote. One will not be voting as they are abroad, while 12 did not respond.
On Monday former shadow home secretary David Davis became the first prominent Conservative to say he would vote against the rise.
Another Conservative MP, Julian Lewis, said on Tuesday he would vote against the proposals. But a third Tory, Ilford North's Lee Scott, has denied reports that he will not back the coalition's proposals.
The National Union of Students is promising to campaign directly against Lib Dem MPs who back the fees increase, arguing that the change will deter people from poorer backgrounds from going to university.
Meanwhile shadow chancellor Alan Johnson - who has previously opposed a graduate tax - has told the Times he believes there is now a "strong case" for one.
Mr Johnson - who steered Labour's legislation introducing tuition fees through the Commons - accused the coalition of "abusing the legacy I left them".
He said: "We are now seeing how casually the variable fees system can be distorted with such damaging effects. It is in these circumstances that there is a strong case for a graduate tax, which may offer a fairer way of sharing costs between individuals and government."
In September, in an open letter to Ed Miliband in the Sunday Independent the day after he was elected Labour leader, Mr Johnson urged him not to introduce a graduate tax: "We should be proud of our brave and correct decision to introduce tuition fees. Students don't pay them, graduates do, when they're earning more than £15,000 a year, at very low rates, stopped from their pay just like a graduate tax, but with the money going where it belongs: to universities rather than the Treasury."