LONDON — GERRY ADAMS appears to be losing his bid to ride the tiger of the Irish Republican Army.
The man who leads Sinn Fein, the political arm of the IRA, had since the 1994 cease-fire in Northern Ireland achieved the image of a peace seeker and gained access to the White House. Yet Friday's bomb attack in London, which ended the 17-month truce, suggests that he has been unable to keep the IRA on the peace track with him.
Now, in Northern Ireland and Ireland, Catholics and Protestants are calling on Mr. Adams to decide whether he heads a movement committed to peace, or one unwilling to forsake violence. (Northern Ireland's Catholics shaken in support for IRA, Page 8.)
His next move will help determine the future of Sinn Fein, whose attitude to IRA violence has always been ambivalent. Adams's credibility as a leader has been ''heavily undermined'' by the IRA's return to violence, said Seamus Mallon, deputy leader of the mainly Catholic Social Democratic and Labour Party, which helped to bring about the peace process in 1994.
''If he is to restore his position,'' Mr. Mallon says, Adams must ''move simply and solely to be the leader of a democratic political party.''
British government officials also say Adams will marginalize himself and Sinn Fein if he fails to speak up against the ''hard men'' who dominate the IRA.
Irish Prime Minister John Bruton, in angry comments on Sunday, said it was now up to Adams to ''persuade the IRA to say the killing must stop.''
As a party, Sinn Fein fought successfully for the independence from Britain of what eventually became the Irish Republic. Sinn Fein's constitution says the party abhors violence, but understands why republicans resort to it to put an end to what they see as colonial rule of Northern Ireland by London.
The ambivalence is mirrored in the recent history of relations between Sinn Fein and the IRA.
In the early 1970s, says Tom Hadden, co-author of the book ''Northern Ireland: the Choice,'' a deep split developed between IRA members who leaned toward peace, and radicals who believed the only way to get British troops out of Northern Ireland was to use guns and bombs.
The latter faction called itself the ''provisional'' IRA, or ''Provos.'' This group now dominates the guerrilla movement.
Mr. Hadden says estimates of the number of Provos in ''active service units'' varies from ''a few hundred to more than a thousand.'' But their secret command structure and support among some Catholics give them influence out of proportion to their numbers.
In the early part of this century, Sinn Fein regarded the IRA as its guerrilla wing, but since the 1970s the balance of authority has shifted to the men and women of violence. Provo guerrillas nowadays see Sinn Fein as their political appendage.
Adams's early background was with the IRA, but he switched to Sinn Fein. In the 1970s, he was imprisoned for his connections with the IRA. He was elected to the British Parliament in 1983 but never took his seat. Adams's aim since the mid-1980s has been to tilt the balance of power back to Sinn Fein.
Adams's political credibility in the eyes of London and Dublin has depended on his ability to make believable political pronouncements on behalf of the IRA.
It emerged at the weekend that MI5, Britain's intelligence organization, warned Prime Minister John Major a month ago that the IRA was likely to renew its campaign of violence.
British government sources said MI5 advised Major that the IRA's seven-man Provisional Army Council (its top decisionmaking body) was unhappy about Adams's political leadership, but that any attacks would be delayed until the end of February.
Adams, who showed signs of being stunned by the IRA bombing in London, appears to have thought the same.
The chorus of calls by London, Dublin, and Northern Ireland's Protestants and Catholics for Adams to commit himself irrevocably to peace puts him in an awkward position, especially if Major continues to push for elections in Northern Ireland. Major was to address Britain on TV last night on the issue.
Sinn Fein, weak in electoral terms, is likely to appear weaker if polls are held soon. The party has no seats in the British Parliament and commands about 12 percent of the Northern Irish vote. The Ulster Unionist Party, meanwhile, holds 13 seats in Parliament and draws support from Northern Ireland's 60 percent Protestant majority.
These figures alone suggest why the unionists favor elections, while the IRA, despite Adams's efforts, appears to have slipped back to relying on the bomb.