His decision came as a surprise even to close colleagues. Mr O'Malley, 54, said he had delayed his move until controversy surrounding his battle with Albert Reynolds, the Taoiseach, over export credits for beef destined for Iraq had died down.
That dispute prompted Mr O'Malley's party to leave the ruling coalition and led to the formation after last November's election of the first Fianna Fail-Labour coalition.
Mr O'Malley said yesterday there were 'absolutely no internal or external factors, personal or political, pressing me to resign. I have chosen this time, a freedom not always available'.
But Dublin commentators feel that since last year's election he faced a long spell of fruitless opposition with Labour and Fianna Fail wedded into an alliance that could last until 2000.
Mr O'Malley, one of the heavy hitters of Irish politics, came into the Dail in 1968. Two years later he was appointed Fianna Fail's Minister for Justice, just as the Northern Ireland troubles were reaching a low point - a period he described yesterday as difficult.
Mr O'Malley was best known until 1986 as the thorn in the side of Charles Haughey, the leader of Fianna Fail, after leading a series of bitterly-fought challenges.
He left Fianna Fail when rejecting the party line opposing liberalising contraception laws and quickly founded his New Right party with a series of mass rallies.Reuse content