THE DREAM of a comprehensive Dublin break through by Fianna Fail in the coming general election is fading rapidly, according to the Irish Times/MRBI opinion poll.

Since he became party leader, Bertie Ahern has helped Fianna Fail make substantial gains on the north side of Dublin, compared with its performance in the 1992 general election. But voters have gravitated towards Fine Gael and the Progressive Democrats on the south side. And, on the basis of poll findings, Fianna Fail would gain only two seats in the capital.

The near collapse of the Labour vote in constituencies north of the Liffey will be even more worrying for Dick Spring. A repetition of that pattern in a general election would jeopardise all five Labour seats on the north side.

The parties likely to gain most from these shifts in opinion are Fine Gael and the Progressive Democrats, with windows of opportunity for the Green Party, Sinn Fein and Independent candidates. Because at most one in four Dubliners have yet to make up their minds on how they will vote, any conclusions are tentative. Figures for a proportional distribution of "undecided" are given in brackets.

Core support for the parties on the north side is Fianna Fail, 40 per cent (52) Fine Gael, 17 per cent (22) Labour, 5 per cent (7) Progressive Democrats, 5 per cent (7) Democratic Left, 1 per cent Green Party, 4 per cent (5) Sinn Fein and Others, 3 per cent each. Twenty four per cent were undecided.

On the south side, 24 per cent were also undecided. There, the core votes of the parties stood at Fianna Fail, 22 per cent (29) Fine Gael, 19 per cent (26) Labour, 11 per cent (15) Progressive Democrats. 12 per cent (16) Democratic Left, 4 per cent (5) Green Party, 2 per cent (3) and Sinn Fein, 3 per cent (4).

Because of the sample size in Dublin (221 voters), the margin of error could be in excess of 3 per cent.

The breakdown of voter intention figures in greater Dublin the first time it has been done by MRBI could spur the Government parties, and Fianna Fail and the PDs, to adopt formal, or informal, voting transfer arrangements before the election. Fine Gael transfers in some constituencies could be of vital importance to Labour and Democratic Left candidates. And the same would hold true for Fianna Fail and the PDs.

The volatility of the electorate is more marked in Dublin than in the rest of the State. As a result of recent election fever, one in five voters outside Dublin entered the "don't know" camp, and this figure grew to almost one in four in the capital.

There is some small consolation for Labour TDs in the fact that, since last June, the party has increased its support, while its main competitors lost ground. The bulk of those moving to the "don't know" category are from Fianna Fail and Fine Gael, are aged under 35 years and are predominantly women.

John Bruton will be extremely by the findings, which show Gael has replaced Labour in the hearts of Dublin voters and is positioned to challenge Fianna Fail on the south side. From a position in the 1992 general election when it trailed Labour in 10 out of the 11 Dublin constituencies, it is now comfortably in front and could gain two seats.

Equally worrying from Labour's viewpoint is the powerful challenge being put in by the Progressive Democrats. Mary Harney told the electorate that, come the next election, the choice would be between the PDs and Labour. On the basis of these figures, the parties are neck and neck in the north side white, south of the Liffey, the PDs are marginally ahead. To capitalise on this situation, the PDs would need high profile candidates.

CRIME and drug related issues will continue to attract public attention over coming months and, in that regard, Sinn Fein's role in public demonstrations and marches is likely to cause concern to the established parties. With a core vote of 3 per cent, the party is in a growth phase.

Dublin will be the cockpit of the general election when it comes. And Fianna Fail's new campaign for the abolition of the Residential Property Tax is clearly designed to appeal to middle class voters south of the Liffey. The PDs have led the charge on the issue, and the party is also ahead in demanding the largest income tax cuts.

With one in four Dublin voters undecided about their allegiances, the spin doctors and the back room boys in all the political parties will be frilly occupied for the next nine months.