The leader of the Ulster Unionist Party (UUP) has said retaining a second unionist seat in next week's European election is under threat.
Robin Swann said non-unionists are trying to gain an extra seat and, if they succeed, it would "encourage Sinn Féin to call for a border poll".
He spoke as the party launched the manifesto for election candidate Danny Kennedy.
The last NI European election returned 3 MEPS - 1 Sinn Féin, 1 DUP, 1 UUP.
The Ulster Unionist Party has concerns that only one unionist will be elected when voters go to the polls next week.
"The second unionist seat is under threat as never before. Non unionists are trying to take it away from us," said Mr Swann.
"That has been very evident in recent media performances where there is an anti-unionist coalition building between other candidates, whose main aim appears to be to ensure there is not a second unionist elected.
"If they succeed, it would encourage Sinn Féin to renew its call for a border poll."
'No deal Brexit must be avoided'
The Ulster Unionist leader made the remarks in front of party members and journalists as he unveiled his party's European election manifesto at a Belfast hotel.
The UUP is fielding veteran Danny Kennedy as its candidate.
The former Stormont minister, who lost his seat at the last assembly election, is hoping to succeed Jim Nicholson, who has retired.
The party said a no-deal Brexit has to be avoided, and it is against a second referendum.
At @uuponline manifesto launch @DKennedy_UUP says he is “ a border unionist “ and says there can not be a return to “ a hard border “.He says unionist concerns about the backstop are valid. Says leaving EU without sensible deal “ not an option”. pic.twitter.com/stVRT2UR5u— Stephen Walker (@StepWalkTV) May 17, 2019
It says any fresh poll on EU membership would be "a travesty for British democracy".
Mr Kennedy told journalists that after Brexit there should not be a border in the Irish Sea, or a hard border between Northern Ireland and the Republic.
In the EU referendum of 2016, the former MLA, like his party, backed remain.
He said people now need to move on.
He told the BBC: "I am at heart a democrat, I am at heart a unionist. And I know I can represent all of the people of Northern Ireland. I know I can represent those who in the past voted to remain and those who voted to leave.
"That debate is over. We have to concentrate on what works best for Northern Ireland."
Voters go to the polls on Thursday 23 May and results for Northern Ireland will be announced on Monday 27 May.