The independent hospital campaigner in West Tyrone, Kieran Deeny, has promised voters he will never lean towards a nationalist or unionist party.
Kieran Deeny is standing as an independent
His comments were accompanied by a public apology over letters sent by Mr Deeny to the SDLP leader Mark Durkan.
In the correspondence he had mentioned the possibility of joining the SDLP in the future.
The comments angered unionist candidates in the constituency.
They were thought to have damaged Mr Deeny's chances of commanding cross-commuity support.
He had asked other parties to stand down their candidates in favour of his campaign to save hospital services in the constituency.
"I may see quite quickly that in Northern Ireland it would be much better to be part of a bigger party to be able to achieve services for people," said the original email.
"So who knows, I could be an SDLP candidate for the next assembly election (whenever that takes place) and that, of course, also could mean the becoming of an SDLP MP."
In a statement released on Saturday to the News Letter, Dr Deeny said he held his hands up about the letters to Mr Durkan which were "wrong and misleading".
"I did so solely, and only, to try and persuade the SDLP leader that his party should not field a candidate in West Tyrone.
"I now apologise unreservedly to all of the good people of West Tyrone and, in particular, those of the unionist tradition, for making these statements.
Mr Deeny said he wanted to make two public promises.
"Firstly, as one who never had any ambition to join the SDLP, I promise now that I will never join the SDLP party nor any of the other N. Ireland parties.
"Secondly, I promise to stay Independent and to represent each and every one of us whether we belong to the unionist, nationalist or other traditions."
Dr Kieran Deeny won an assembly seat in 2003
The West Tyrone seat is also being contested by the DUP's Tom Buchanan and the Ulster Unionist's Derek Hussey.
Eugene McMenamin has been selected to run for the SDLP and the outgoing MP, Pat Doherty, is running again for Sinn Fein.