Barry Walsh has resigned from the Fine Gael Executive Council following controversy over some of his tweets.
It had emerged that Mr Walsh had sent tweets to female politicians, including those in his own party, using words such as 'bitch'.
In a statement, the chairman of the party council confirmed he had received and accepted Mr Walsh's resignation.
In his resignation letter, Mr Walsh says he deeply regrets the tone and language used in some of his tweets.
He wrote: "I realise that some of my remarks have caused serious offence to many people and I apologise unreservedly for that.
"I first got involved in politics because I have passionate views on many issues and have always enjoyed robust political debate, however I accept that with many of these tweets I took the political jousting a step too far."
Earlier today, Taoiseach Leo Varadkar had called on Mr Walsh to resign.
