Tony Blair will tomorrow make a last personal appeal to rebel Labour MPs not to plunge his Government into crisis by voting down controversial plans for university tuition fees.

The Prime Minister was spending 90 minutes tonight trying to woo the doubters and will return to the task tomorrow, after Downing Street admitted the vote was "too close to call".

Mr Blair’s official spokesman, asked today if No 10 was confident of winning tomorrow night’s crunch vote on the Higher Education Bill, admitted: "We hope so. But we don’t know so."

Complex games of bluff and counter-bluff were being played out tonight at Westminster in a high stakes poker game unheard of for a Government with a nominal majority of 161.

If Mr Blair loses tomorrow night’s vote it will be only the fourth time in the last 100 years that a Government with so vast a majority will have lost a Bill on its Commons second reading, which deals with a measure’s fundamental principles.

Charles Clarke, the Education Secretary, has spent days fine-tuning concessions on the Bill, and may yet announce more in the Commons tomorrow.

But so far his assurances on capping fees to £3,000 per year unless both Houses of Parliament agree and the promise of an independent review of the system in 2009 have not convinced many wavering MPs.

Mr Clarke tonight announced details of his promised review of the first three years’ operation of the new policy.

In a written ministerial statement, he said that the review, to be conducted by an independent commission would look at the impact of tuition fees on the overall levels of application and participation in higher education.

It would also consider student support arrangements, including those for students from the poorest backgrounds as well as those above the threshold for Government support.

It would examine the levels of debts of students leaving university, and the effect they had on their subsequent choice of employment, as well as making recommendations on any changes to the upper limit for tuition fees.

Gordon Brown, the Chancellor, today threw his weight publicly behind Mr Blair again, despite suspicions that some of his supporters are orchestrating the "no" vote campaign to wound the Prime Minister in a crucial week which will test his authority.

Lord Hutton reports on Wednesday on the death of weapons expert Dr David Kelly - with Mr Blair, his Downing Street staff past and present and ministers, such as Geoff Hoon, the Defence Secretary, effectively in the dock.

The Chancellor told a London conference on enterprise: "I want us to be the best educated, best trained workforce, and tomorrow’s much-needed reform of university finance - which I urge all MPs and all Labour MPs to support - is another vital step towards that goal."

Mr Blair’s spokesman said later: "You can certainly take it the Prime Minister has been speaking to colleagues over the last few weeks and over the weekend and that will continue today.

"The Prime Minister has put in, and is continuing to put in, a lot of effort to ensure that the Government’s legislation is carried tomorrow.

"We just have to wait and see what tomorrow heralds."

Asked about Mr Blair’s confidence of winning the vote, the spokesman replied: "We hope so. But we don’t know so.

"Clearly as things stood last week the numbers were not there and that’s been well documented.

"A lot of MPs went back over the weekend to their constituencies, no doubt they will have spoken to their constituents and they will come back today.

"The short answer is it’s too close to call. I wouldn’t want to make any prediction."

As Mr Blair was talking to backbenchers tonight in his room in the Commons, his spokesman added: "I would imagine he will be speaking to people tomorrow as well. The dialogue is pretty continuous from the Government side."

The Prime Minister will be at Mr Clarke’s side on the Commons front bench tomorrow when he introduces the Bill, and ministers have been ordered back from foreign engagements to be present at the vote at 7pm.