His predecessor in the office, Charles Haughey, systematically reviewed, repealed or amended Acts dating back 700 years in the single largest reform of the Irish civil and criminal code ever undertaken.

Lenihan carried the legislative programme, covering everything from repealing mediæval laws to granting succession rights to married women.

[a] The scheme was abandoned after mass opposition, Lenihan famously being forced to flee student protests in Trinity through a toilet window.

Haughey, seeking to weaken the faction supporting Colley, appointed Lenihan as Minister for Foreign Affairs, a post he held until Fianna Fáil lost power in 1981.

His period in Foreign Affairs was overshadowed by a comment made after an Anglo-Irish summit between Haughey and British Prime Minister Margaret Thatcher, when he spoke of Britain and Ireland being able to bring about Irish unity within ten years, a comment which infuriated the British and Northern Ireland unionists and which undid much of the goodwill achieved by the summit.

[8] In 1982, when Fianna Fáil regained power for what would prove only ten months, Lenihan was appointed Minister for Agriculture, the announcement in the Dáil being greeted by a sustained round of laughter on the opposition benches.

[citation needed] In opposition, Lenihan and Haughey attracted some international criticism when, against the advice of senior Irish-American politicians Senator Edward Kennedy and Speaker Tip O'Neill, they campaigned against the Anglo-Irish Agreement, which the government of Taoiseach Garret FitzGerald had signed with the British government of Prime Minister Margaret Thatcher.

It was revealed subsequently that Lenihan's operation was partly paid for through fundraising by Taoiseach Charles Haughey, from businessmen with Fianna Fáil links.

[9] Haughey was revealed in the 2006 tribunal report to have been engaged in numerous acts of corruption, to finance a lifestyle considerably in excess of his earnings as a politician.

In January 1990, leaks to the media suggested that Lenihan was considering seeking the Fianna Fáil nomination in the 1990 presidential election, which was due in November 1990.

Speculation abounded that this was part of a plan to discourage other parties from running candidates in the belief that Lenihan would prove unbeatable and so get the office unopposed.

[10] Lenihan was generally perceived as an unbeatable candidate, though he did receive a late challenge for the nomination from cabinet colleague John Wilson.

The main opposition party, Fine Gael chose Austin Currie, a TD and former Northern Ireland cabinet minister, to be its candidate.

In September 1990, The Irish Times carried a series of articles on the presidency, one of which mentioned in passing the role of Lenihan, Sylvester Barrett, and Charles Haughey in making the calls.

In an interview in the Irish Press and on RTÉ's Questions and Answers programme, he insisted that he had had "no hand, act or part" in efforts to pressure President Hillery.

He appeared on a live TV news bulletin, and, looking into the camera, pleaded with the Irish people to believe him, stating that "on mature recollection" he had not phoned President Hillery and his account to Duffy had been wrong.

The Progressive Democrats, Fianna Fáil's coalition partner, told Taoiseach Charles Haughey that unless Lenihan was either dismissed or an inquiry set up into the events of January 1982, it would pull out of government, support the opposition motion and force a general election.

Many in Fianna Fáil were disgusted with what they saw as Haughey's betrayal of his old friend, and argued that the Progressive Democrats' threat to bring down the government was a mere bluff.

A personal attack by former cabinet colleague Pádraig Flynn on Mary Robinson, in which he accused her of showing a "new-found interest" in her family, backfired and destroyed Lenihan's campaign.

However, most of the votes that initially went to Austin Currie, the third-placed candidate, transferred to Mary Robinson on the second count, in what was widely seen as a pact between Fine Gael and the Labour Party.

Bitter at what he saw as his betrayal by the Progressive Democrats, he campaigned[citation needed] for Fianna Fáil to go into coalition with the Labour Party instead, something which happened after the 1992 general election.