A former Lagan Valley Sinn Féin MLA has called for his party and the SDLP to stand aside in the constituency in the next general election.
Paul Butler, an MLA for four years to 2011 and formerly a long-time councillor, argued the Alliance Party should be allowed a "free run" to take the seat currently held by DUP leader Jeffrey Donaldson.
The one time IRA prisoner's intervention came after Alliance leader Naomi Long predicted her party's likely candidate in next year's election, Sorcha Eastwood, could take the seat.
Mr Butler wrote on social media: "Sinn Féin and the SDLP should stand aside in Lagan Valley at the next general election and let the Alliance Party have a free run to take Donaldson's seat."
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The SDLP and Sinn Féin did not immediately respond to request for comment on Mr Butler's call for the party's to stand aside in the election, which has to be take place before next December.
An Alliance Party spokesperson has said: "Alliance has always been clear that we don’t engage in pacts. We will be running in all 18 constituencies, and we believe it is for the electorate to freely decide who represents them in the House of Commons.”
At her party's annual conference in Enniskillen, Ms Long said: "Anyone who watched Sorcha Eastwood demolish Jeffrey Donaldson with his own words on Thursday’s Question Time can be in no doubt that Alliance can win that seat.
“Anyone who watched Jeffrey nervously drinking his water while she did, or heard the DUP attacks that focused intensely on Alliance at their conference last week, will be in no doubt that the DUP believe we can too."
East Antrim DUP MLA Gordon Lyons, also his party's director of elections, described the Alliance leader's comments as "typical arrogance".
"The Alliance Party’s disregard for the views of unionists will not be forgotten at the polls. Alliance didn’t call to exclude nationalists when SF collapsed Stormont over the Irish language yet when unionists are unhappy, the Alliance Party are straight to the microphone calling for unionists to be excluded from the Executive," Mr Lyons said.
Ms Long's comments prompted the Ulster Unionist's Robbie Butler, a Lagan Valley MLA, to describe the position as "condescending" to the voters of the constituency.
He pointed out on social media there were seven candidates in the last election and argue "voters have consistently over the past 4 years voted in increasing numbers for the Lagan Valley #UUP team".
"We don’t do fairytales, we work hard," Mr Butler added.