text: In the 2017 Assembly election that followed McGuinness's resignation, O'Neill was returned to the Assembly, topping the poll in Mid Ulster and with a 20.6% share of first-preference votes. In March 2017, she called for a referendum on the reunification of Ireland "as soon as possible" in response to Brexit. O'Neill led the Sinn Féin side in the inter-party negotiations that followed the election, aiming to restore a power-sharing coalition in Northern Ireland, but said at the end of March that the talks had failed, and Sinn Féin would not nominate her for the position of deputy First Minister.
  In February 2018, O'Neill became vice president of Sinn Féin, succeeding Mary Lou McDonald, who became president following the retirement of Gerry Adams. In November 2019 she faced a leadership challenge from John O'Dowd, winning with 67% of the vote.
  Deputy First Minister of Northern Ireland
  In January 2020, O'Neill was appointed deputy First Minister of Northern Ireland. She automatically lost her position on 14 June 2021 when Arlene Foster resigned as First Minister, and regained it three days later when she and Paul Givan were nominated as deputy First Minister and First Minister respectively on 17 June 2021. In February 2022, O'Neill once again lost her position as deputy First Minister with the resignation of Paul Givan as First Minister.
  First Minister of Northern Ireland