In a statement issued late on Thursday night, Ms Wynne, a first-time TD in the Clare constituency, said she had not renewed her membership of Sinn Féin and made several specific allegations against the party and how it treated her since she was elected to the Dáil in 2020.
Ms Wynne, who recently gave birth to her sixth child and said she is on “some form of maternity leave”, claimed the party did not support her after she entered the Dáil.
Sinn Féin has been contacted for comment by Independent.ie
In her statement Ms Wynne said: “I was a proud Sinn Féin TD and took my membership with the party very seriously, I believed that they were the party for United Irelanders and were the future for this island. I now have experience that I can no longer ignore that states otherwise.
“I entered Leinster House coming from the dole to the Dáil after navigating with great difficulties and with what many may call baggage which I was clear and honest about to the local representatives of the organisation at the time, from the start.”
She continued: “I had assumed that after the election in 2020 I would receive support as I had clearly received the mandate from the people of Clare.
She outlined her view that Sinn Féin “do not take kindly to autonomy and those who do not follow their plans”.
“The Sinn Féin TDs in Leinster House I cannot fault but they are not tasked with making decisions locally and seem to be an entirely separate entity with no power to influence. The issues I continuously faced seem to be at local level within the organisation and structures and lack of,” Ms Wynne said.
She said she believed that some in the party wanted her to stand down and “have been actively seeking this through gaslighting measures and what can only be described as psychological warfare”.
Her statement continued: “I have tried to force the comradery and on many occasions, I informed them of the impact of their actions on my personal well-being and my work, but it was to no avail.
“I feel I have been isolated and steps have been taken to ensure that I would face greater difficulties, locally.
“This is not a decision that I have taken lightly, and I have battled with the party for many months now trying to avoid this course of action as I wholeheartedly believed in them.”
Ms Wynne said that her membership of Sinn Féin had become "untenable" but added she will continue to represent the people of Clare, saying she hoped that they would see “a better representative with no obstacles put in my way any longer”.
Earlier this month Ms Wynne described how she gave birth to a baby girl with the help of a local ambulance service in a car park.
Ms Wynne had already started her maternity leave, but her due date was not until March. She gave birth to a girl named Collins or ‘Collie’ and told RTÉ’s Drivetime programme she was “still living on the high of giving birth”.
Last year she received an apology from Tánaiste Leo Varadkar after he incorrectly claimed that Sinn Féin has no Protestant TDs. Ms Wynne, who is a Protestant, complained about the remarks.
She previously courted controversy over old social media comments where she compared the dangers posed by the "ingredients" in vaccinations to changing where you buy coffee. She later said the posts made several years ago did not reflect her current views or Sinn Féin policy. Ms Wynne said at the time she would take the Covid-19 vaccine.