Fianna Fáil's support was damaged by high-profile controversies, such as 'Votegate', and the stance of many party TDs on repealing of the Eighth Amendment a review of the party has found.
According to The Irish Times, the report, based on a review of electoral performance and a survey of members, found support for the party among young people was negatively impacted in the run-up to the abortion referendum.
The 'Votegate' controversy in 2019, during which party TDs were found to be voting in the Dáil chamber on behalf of absent colleagues, was another issue given as a reason for poor electoral performance, in addition to talking too much about "another party", Sinn Féin, during the 2020 General Election campaign.
The report has been circulated to Fianna Fáil members ahead of a party think-tank later today in Co Cavan.
The party's leadership also comes under fire in the report, which highlights the late appointment fo a director of elections, a cautious manifesto and an ineffective use of social media as factors contributing to the poor election performance.
Party identify is also described as weak, claiming the majority of members are unclear about it, adding Fianna Fáil relies heavily on "candidate-based voting" as opposed to strong party support.
That support was also said to have been impacted by the confidence and supply arrangement with Fine Gael prior to the 2020 election, which meant Fianna Fáil could not assert an independent position in opposition, according to the report.
Party leader, Taoiseach Micheál Martin is expected to face severe criticism at the meeting of TDs and Senators in Cavan, with The Irish Times reporting sources have speculated there could be a motion of no confidence in him. However, that prospect was played down on Wednesday night by sources said to be opposed to Mr Martin's leadership.