By Nick Assinder BBC News Online political correspondent

He tries to hide it, but you can still see Tony Blair positively glowing whenever he is compared with Margaret Thatcher.

But - while his critics claim he can't wait for his own Falklands or even his own miners' strike - the last thing he wants to replicate is the former prime minister's poll tax disaster.

And there are now the first signs that he has spotted the oncoming express train in the shape of university top-up fees.

Thatcher was damaged by poll tax

As students marched through London in opposition to the suggestion, the chairman of the education select committee, Barry Sheerman, said he believed the government was going off the idea.

The truth is that a large slice of the government and an even bigger slice of the Labour backbenches were never on the idea in the first place.

Blair v Brown

Hardly a day goes by without another senior backbencher or frontbencher expressing their opposition to the suggestion.

The obvious cabinet split has focussed on the inevitable Blair versus Brown battle.

That has not been helped by the fact that the chancellor has done nothing to deny his claimed opposition to top up fees.

Students have been politicised

And it is no coincidence that many of those opposing the proposal are Brownies.

The idea has even managed what many believed was impossible and politicised the once-radical but now deeply conservative student movement.

Meanwhile, as all this mayhem has been breaking around his head, the prime minister has refused to rule out the possibility of introducing such fees.

Market place

He insists that people must await the publication of the White Paper in January which will set out the possible options.

But, at the same time, he has been stressing that no one challenges the urgent need to get extra cash into the country's universities if they are: "To compete in the global market place."

He seems unhappy, however, to address the possibility of funding higher education through general taxation.

Blair: may be re-thinking

That language is itself not designed to placate those who believe education should not be "privatised".

And rumours that the prime minister was digging in on this one also increased the temperature.

It is highly likely and understandable that Mr Blair does not want to be seen losing out in a battle with his leadership rival Gordon Brown.

But, with talk of "Tony's poll tax" growing by the day, he may find the strength of the opposition overpowering.

Probably better to stage a strategic withdrawal and take the flak than risk the same sort of crisis that engulfed Margaret Thatcher.