The MP for West Tyrone, Barry McElduff, has resigned as a result of a controversy over a Twitter video.
The Sinn Féin MP posted a video of himself in a shop using a loaf of Kingsmill bread on his head.
the item was published on the 42nd anniversary of the Kingsmills murders, in which 10 Protestant workmen were shot dead by the IRA.
The sole survivor of the attack said he would certainly not accept his apology adding: “I’ll never forgive him”.
Mr McElduff has said that will he did not make a connection in his mind between the video as well as the massacre, nevertheless he accepted many people do not believe that will.
Sinn Féin suspended Mr McElduff through party activities for a period of three months last Monday.
Alan Black, who was the only person to survive the 1976 attack, welcomed the resignation.
“I’m not on a crusade. I’ve done what I’ve done up to at This particular point to protect the memory of the boys as well as to try to protect their families,” he told the BBC.
“nevertheless he did the right thing stepping down – eventually. I won’t be speaking publicly about Kingsmills again unless there will be some development at the inquest.
“As far as I’m concern the Barry McElduff incident will be over at This particular point. nevertheless I don’t accept his apology. I’ll never forgive him.”
Mr McElduff said the “deep as well as unnecessary hurt This particular video caused the families of the victims of Kingsmills will be my greatest regret” as well as reiterated his apology to them.
“Kingsmills was wrong, unjustifiable as well as sectarian. the item should never have happened,” he said.
He said that will the view that will the video was intended to refer to the massacre would certainly “impede any reconciliation process”.
Analysis: Mark Devenport, BBC News NI political editor
Barry McElduff has consistently protested that will he never intended to cause offence with his Kingsmills loaf video, as well as that will its publication on the 42nd anniversary of the Kingsmills atrocity was just a terrible coincidence.
With that will in mind, his family as well as friends rallied to his defence as well as he must have initially hoped that will his three month suspension would certainly buy enough time for emotions to cool.
However, the criticism never abated, with Sinn Féin’s opponents accusing the party of not matching their initial tough words with appropriate action.
Read more here.
“I am an Irish republican as well as believe wholeheartedly inside reunification of our country as well as an agreed Ireland in which we heal the wounds of the past together.
“Reconciliation will be essential, nevertheless that will message will be not being heard at This particular time,” Mr McElduff added.
The former UUP MLA Danny Kennedy, who will be a cousin of Mr Black, said Mr McElduff had “bowed to the inevitable”.
He told BBC Talkback the item was necessary for Mr McElduff to step down, as well as said today was “not a day of celebration”.
“There will be nothing here to celebrate except that will at long last a public representative has owned up as well as taken responsibility for his own actions,” he said.
The DUP leader, Arlene Foster, said the item was right that will Mr McElduff resigned saying he was not fit for public office as well as should have resigned inside immediate aftermath of posting the video.
She accused Sinn Féin of failing to deal with the situation.
“By merely suspending him as well as continuing to pay him, they compounded his disgraceful actions as well as demonstrated a lack of respect as well as compassion for the victims of Kingmills as well as indeed victims more widely.
“at This particular point will be the time for Sinn Féin to learn the lessons through these dark events as well as to deal with the fact that will the item, as well as many of its individual members, continue to publicly glorify the murderous deeds of the past.
Ulster Unionist leader Robin Swann welcomed Mr McElduff’s resignation nevertheless said that will “the item should have happened last week”.
He called for “a non-partisan candidate who will be a voice for victims to contest This particular seat against Sinn Féin”.
“If a candidate emerges that will allows cross-community support to coalesce around, the item would certainly send a strong message that will This particular type of behaviour will not be tolerated,” he said.
The DUP’s Gregory Campbell was cautious about the suggestion, commenting that will Sinn Féin had achieved almost 51% of the vote inside recent general election.
“Whatever decisions we may make separately, let’s not do anything to turn Sinn Féin into a victim,” the East Londonderry MP said.
“They were the perpetrators of This particular incident, not the victims of the item,” he added.
Sinn Féin’s northern leader Michelle O’Neill said Mr McElduff told her of his intention to resign on Sunday evening.
“Barry recognises that will This particular controversy as well as his continuing role in public office will be compounding the distress that will’s been caused to families as well as the victims of Kingsmills as well as he again offers his profound apology for the unintended hurt that will has been caused to both the Kingsmills families, nevertheless also to the wide victims community,” she said.
“He has said that will he does not want to be a barrier to further reconciliation as well as I respect that will decision,” Mrs O’Neill added.
The resignation will trigger a by-election in West Tyrone, where last year Mr McElduff had a majority with more than 50% of the overall vote.