Micheal Martin has dismissed him as “no loss”, but when a name like Andrews jumps ship it raises eyebrows.
Chris Andrews said he wanted “to make a statement” as he tries to explain why he would guillotine a family tradition that dates back to the foundation of Fianna Fail and cross the divide to Sinn Fein.
His grandfather Todd Andrews was a leading figure in the early days of Fianna Fail.
His father Niall and uncle David were both well-known ministers and his first cousin Barry was Children's Minister until the party imploded at the last election.
For the record, Late Late Show host Ryan Tubridy is also a cousin.
“There’s no denying that it was a big decision, a tough decision. There were a lot of emotions around it,” Andrews says.
“But when you took away those emotions and look at it rationally it was the right one for me, I believe.”
The 49-year-old ex-Dublin East TD struggles to explain the background to the move.
“I had a couple of options. One of them was to do nothing and I’m not the type of person who does nothing.
“I could have gone independent and in many ways that would have been the easy option. If I'm talking about change and advocating change then I have to be |willing to make some change myself.
“Dublin 4 wouldn’t be associated with a bedrock of Sinn Fein support. It wasn't the easy option.”
There were no discussions with Gerry Adams – who Andrews admits to criticising on Twitter using a fake account – before or after he applied for party membership.
He says those tweets – which included mention of murdered mother-of-10 Jean McConville and the Northern Bank robbery – are now “water under the bridge”.
Pressed on what he expects to get from Sinn Fein, he insists that no deal has been done and he has not even been assured of a place on the Sinn Fein ticket for next year's city council elections.
“If I were just looking at political ambition, Sinn Fein in Dublin 4 would not be a starting point,” he says.
At the same time he outlines his priorities as the needs of community groups, small businesses and families who can't get flood insurance on their homes.
He is currently doing a three-year degree course in community development and Youth Affairs in Maynooth.
“So many people were left behind in the boom and now they are being left behind in this recession,” he says, almost as if he was canvassing, before attacking Fine Gael, Labour and Fianna Fail arguing there is a “cigarette paper difference” between them.
But what does his family, a Fianna Fail dynasty, really make of the move?
It has caused arguments and some have not been enthusiastic. However, he suggests that there is “no doubt” that his late grandfather would have supported him.
“It's like any family, there's a diversity of views and there's arguments and discussion. Some thought it was a great idea, some didn't think it was a great idea.”
His grandfather “ate, drank and slept” politics and was an “extremely strong republican”.
“I'd like to think that he wouldn't be unhappy with my decision. I think he would have understood it.”
He adds that he's “positive” Todd Andrews would be “very disappointed with the direction Fianna Fail has taken and in particular, its support for the vested interests – big business, banks, etc, at the expense of the ordinary middle and working class communities which were traditionally Fianna Fail’s bedrock of |support”.
He denies that the Sinn Fein brand could “tarnish” the family reputation.
“I don't think you can be tarnished by being involved in politics. Being involved in politics is a good thing. It's unbelievably important.”
He claims that the support from many friends within Fianna Fail has been overwhelming – but Micheal |Martin is certainly not one of them.
“Micheal has his own agenda. He's a politician,” says Andrews in a very blatant swipe at the former minister.
“In Fianna Fail the current leadership wants change but only for the little people, not for themselves.”
Having topped the poll in 2007 ahead of Lucinda Creighton, Ruairi Quinn, John Gormley and Michael McDowell (who lost his seat) Andrews became an outspoken backbencher in the latter half of the Bertie Ahern/Brian Cowen government.
But he never found it in himself to vote against the party whip. He now describes voting for savage austerity as his “biggest regret”.
“I should have left before I did but in hindsight it's easier said than done and that emotional tie. It's hard to explain.”
He thinks before adding: “I put a lot into loyalty but there is also blind loyalty which is unhealthy.”
Although he remained a member of the party after the election, Andrews showed very little loyalty to Martin and was eventually outed as the creator of a phoney Twitter account used to criticise senior party figures.
“It was the wrong thing to do. I said then it was a mistake and there's not a whole lot more I can say on that.”
With an almost philosophical tone he concludes: “I'm far from perfect but I am willing to change. I've made mistakes. I'll continue to make mistakes. It's human nature.
“I'll learn from those mistakes. I should be a genius at this stage.”
By Kevin Doyle