London — Successive Irish governments have long dreaded that once Sinn Fein established a beachhead in the north, it would turn its attention to the south to expand its political base and spread its revolutionary message. That moment has come with the decision by Sinn Fein (the political arm of the outlawed Provisional Irish Republican Army) to take seats, if elected, in the D'ail (the Republic of Ireland's lower house of Parliament).
The move was approved by more than the necessary two-thirds members at Sinn Fein's Dublin conference last weekend. But traditionalists who want nothing of constitutional politics - especially since the D'ail recognizes, in practice, the division of Ireland - feel betrayed. Some of them have split to form the new Republican Sinn Fein.
The decision to play constitutional politics is more of an embarrassment than a help to Irish Prime Minister Garret FitzGerald.
It introduces a radical party that embraces Marxist solutions to a politically conservative society in which differences between ruling Fine Gael and the opposition Fianna F'ail are more historical than ideological. The concern of Irish politicians is that Sinn Fein may become the underdog's party by exploiting Irish poverty and its unemployment - the highest in the European Community.
If Sinn Fein garners a respectable vote, it would further complicate Dr. Fitzgerald's position. Since signing the Anglo-Irish agreement almost a year ago, FitzGerald has worked hard to play down nationalist sentiments in his country in order to placate Northern Ireland Protestants. The Ulster unionists, as the Northern Ireland Protestants are known, wish to keep their ties with Britain. They see the 1985 deal between London and Dublin as an attempt to foist a united Ireland on them.
Ironically, a principal aim of the Anglo-Irish agreement was to undercut the growing political strength of Sinn Fein by throwing a lifeline to the moderate, largely Roman Catholic Social Democratic Labour Party (SDLP). The idea was that aggrieved Catholics might now look to Dublin, not the IRA, to protect their interests.
For both London and Dublin, one of the payoffs of the agreement was that in the first electoral test, thousands of Sinn Fein supporters switched their votes to the SDLP.
Sinn Fein's debut in Northern Ireland constitutional politics in recent years was a direct response to a dual strategy, embraced in 1981 by the northern leadership, of the ``Armalite (rifle) in one hand and the ballot box in the other.''
A Sinn Fein representative in Belfast once said his organization canvassed voters to disprove the British government's theory that the IRA's appeal was limited only to a few hundred terrorists.
In Northern Ireland, Sinn Fein has garnered as many as 100,000 votes in one election, a development that threatened the SDLP's status as the majority Catholic party.
The challenge facing Sinn Fein's political opponents in the south, as much as the north, is that it is very effective at the community level. Sinn Fein's ability to draw votes, observers say, has more to do with its energy in trying to resolve local issues than with radicalizing the electorate.
In elections in Northern Ireland last year, Sinn Fein returned 59 councillors to 17 of Northern Ireland's 26 Council chambers. Unionists liken the Sinn Fein councillors to ``gunmen in pinstripe suits.'' Sinn Fein Councillor Gerry Doherty took his seat in Londonderry's Guildhall which he once blew up.
Under Gerry Adams, Sinn Fein has adopted a more sophisticated image. Mr. Adams justifies Sinn Fein's decision to end the boycott of the D'ail as part of a new political realism.