In April 2022, shortly before the 2022 Assembly election, all of the DUP's officers in South Down refused to endorse the party's candidate Forsythe and resigned from the DUP.[4] They claimed that Forsythe was "imposed" on them by the DUP without proper consultation.
The Police Service of Northern Ireland launched an investigation into "a defamatory message" being shared about Forsythe during the election campaign.[5]
On 5 May 2022, Diane Forsythe was elected as the new Democratic Unionist Party MLA for the South Down Constituency. She polled 6,497 first preference votes, and was elected on the 6th count with 11,073 votes. She became the first female unionist MLA for the constituency.[6]
She was the DUP's candidate in South Down at the 2024 general election, coming third with 7,349 votes (16.2%)[7][8]