Nobody likes to fall out with friends. Not even political ones. As somebody who values friendship and loyalty, the Taoiseach, Mr Ahern, found himself in an awkward position yesterday.

Flanking him at a key meeting in Government buildings on the future of the semi-state sector was arguably his most loyal and long-standing lieutenant, Minister for Transport, Mr Brennan.

On his other side was the country's most senior trade union figure, ICTU's Mr David Begg - a key player in the industrial relations world and someone who Mr Ahern has worked closely with in the past six months.

The Taoiseach, the essential consensus man, is stuck between the two of them - literally and metaphorically. With such a politically charged issue at stake, Mr Ahern may have to disappoint one of them - not something he likes to do, unless you count the occasional cabinet re-shuffle.

Mr Brennan, the Taoiseach's chief whip, was the glue that held the last Government together. At endless meetings each week, he was able to keep unpredictable independents like Jackie Healy Rae and Harry Blaney happy, or at least happy enough not to vote against the Government.

Consequently Mr Ahern owes a certain political debt to Mr Brennan, and the battle over CIÉ and Aer Rianta is the first test of whether he is prepared to pay up.

The Brennan camp are extremely anxious to press ahead with the breakup of CIÉ and Aer Rianta, and there is some talk in political circles that if Mr Ahern does not back up his transport minister, Mr Brennan might reconsider his position.

Nobody will say that officially, but Mr Brennan's problem is that, after going out so publicly on the issues of CIÉ and the airports, how can he retreat now without losing serious political credibility?

If the issues were simple and the personalities different, it would probably be easy for the Taoiseach to give the minister his blessing. But the problem is, the Taoiseach owes Mr Begg, as ICTU general secretary, a few favours too.

Earlier this year when it appeared the social partnership deal, Sustaining Progress, could be lost, the Taoiseach sent Mr Begg a letter, which some trade unionists believe allowed Mr Begg to sell the deal to some of the more reluctant unions.

The letter of February 10th was distributed widely and it addressed the issue of change in the semi-state sector. Mr Ahern said in the letter he appreciated the significance that ICTU attached to dialogue on the future of semi-states and all discussions should be grounded on four principles. Mr Begg interpreted this letter for his union colleagues and his work essentially paved the way for the deal to go through by 231 Congress votes to 150. Mr Ahern must have been grateful.

Since then, Mr Begg has been unhappy, claiming that Mr Brennan's approach has undermined the assurances he personally gave his trade union colleagues at that pivotal moment.

In a letter on April 4th to Mr Ahern, disclosed in this paper, Mr Begg wrote: "You are aware that this letter was key to achieving majority support for Sustaining Progress within Congress."

He then said to Mr Ahern: "I do not doubt your personal bona fides with regard to your letter of February 10th, but we have to deal with the Government as a whole." The Government "as a whole" was a fairly obvious reference to the Taoiseach's transport minister.

The CIÉ and Aer Rianta unions believe the four principals enunciated by the Taoiseach in the original letter have been broken by Mr Brennan. One of them said the Government's policy would not be based on "any ideological assumption", while another said there should be a "strategy for sharing information and analysis" between the unions and Government.

With Mr Brennan spending a lot of time explaining his break-up plans to the public and the media, the unions are angry that their views do not appear to be getting a fair hearing. They claim that the minister has his mind made up and he is not taking their views seriously. This is rejected by Mr Brennan.

Mr Begg, while not personally critical of the minister, has expressed concerns about the indecent haste from Department of Transport. As a trade union leader, he is also concerned that job losses could occur at the airport if things are not done properly.

Most alarmingly from the Taoiseach's point of view, Mr Begg has warned that "industrial confrontation" in the semi-state sector could threaten the very survival of the national agreement.

While Government sources are somewhat sceptical about this, the Taoiseach is likely to take Mr Begg's views seriously - but will he take them more seriously than the counter arguments put forward by his minister?

"\ Brennan has done his ground work and would surely not have gone this far if the Taoiseach was not behind him," said one source yesterday. They point out that the Taoiseach, Mr Brennan and the Minister for Finance, Mr McCreevy, are all on a Cabinet sub-committee on transport, and there is no way that Mr Brennan would be making such bold statements without first checking with his political line manager.

"There are several ways to skin a cat, Bertie will probably back Brennan, but he may tackle the issues more softly and in a less confrontational style," the source continued.

However, the Taoiseach will find it hard to bridge the chasm between his minister and the unions. There is little common ground.

Mr Brennan has made it clear that he is determined to break up CIÉ and Aer Rianta, and to offer private companies the chance to build a new terminal at Dublin Airport.

The implacability of the minister is matched by the unions, who claim his plans will cost the Exchequer millions, with the CIÉ break-up likely to cost up to €500 million.

If the Taoiseach can find common ground between those two positions, his reputation as a fixer would move up several notches.

The unions claim that Mr Brennan has not thought his plans out and should pay more heed to what has happened to the transport system in Britain, where safety and efficiency have been compromised.

But Mr Brennan has said the Government cannot stand over monopolies at Dublin airport and in the Dublin bus market. He has explained his views in trenchant and passionate terms, and maybe soon we will find out if the Taoiseach truly shares them.