The Taoiseach, Mr Ahern, will be presented with an opportunity to reshuffle his Cabinet next week following the decision of Mr Andrews to resign as Minister for Foreign Affairs.
Mr Andrews, who will formally retire on Wednesday, informed Mr Ahern by telephone last night of his decision. He did this to end speculation about his position since the July announcement that he would not be seeking re-election to the Dail at the next general election.
Mr Andrews, 65 next March, said that when the Taoiseach "goes into the next election he should be in a position to present his future cabinet team to the electorate".
He said the Belfast Agreement was the achievement which gave him "huge personal fulfilment".
There was speculation in political circles last night about what approach Mr Ahern would adopt following the Cabinet vacancy created by Mr Andrews's decision.
In September 1997, when Mr Ray Burke was forced to resign in controversial circumstances as Minister for Foreign Affairs, Mr Ahern opted for minimal movements. However, as the Government is now in the middle of its term, Mr Ahern may consider introducing new faces at Cabinet and Minister of State level.
The front runner to take over at Foreign Affairs is the Minister for Health, Mr Cowen, although the Minister for Public Enterprise, Ms O'Rourke, may be considered for the position.
On seniority, the Government chief whip, Mr Seamus Brennan, could expect to be promoted to the vacant Cabinet post. However, Mr Ahern may be unwilling to move him from a position in which he has successfully managed to maintain cordial relations with the four independents who have deals to support the minority Coalition.
Several Fianna Fail backbench TDs will be hoping for promotion to Minister of State rank, including Dublin deputies Mr Brian Lenihan and Mr Eoin Ryan. However, political considerations in Mr Andrews's Dun Laoghaire constituency may make ail TD, Ms Mary Hanafin favourite for promotion.
Mr Andrews was first elected to the Dail in 1965. He has contested 11 general elections and served at Minister and Minister of State level in governments led by Mr Jack Lynch, Mr Albert Reynolds and Mr Ahern.
He was Government chief Whip from 1970 to 1973. When Fianna Fail returned to office in 1977, he was appointed Minister of State for Foreign Affairs.
Following the election of Mr Charles Haughey as Taoiseach in 1979, Mr Andrews's political ambitions were stifled. He was a long-time opponent of Mr Haughey as leader of Fianna Fail and remained on the backbenches during his leadership.
However, his political career was revitalised in February 1992 when Mr Reynolds became Taoiseach. He served as Minister for Foreign Affairs until the formation of the Fianna Fail-Labour government in late 1993, when he was appointed Minister for Defence and the Marine.
When the current Fianna Fail/Progressive Democrat Coalition was formed in June 1997, Mr Andrews returned to the Department of Foreign Affairs.
Last night, Mr Andrews said he owed "a deep debt of gratitude" to his wife, Annette, who, along with the rest of his family, gave him total support throughout his 35 years in public life.