DUBLIN, Ireland (Reuters) - When Michael O'Byrne's son finishes a PhD at Britain's Cambridge University next year, he plans to return home to Dublin to try and win a seat for Sinn Fein at the 2014 local government elections.
It is an unlikely background for a career in the one-time political wing of the Irish Republican Army, the guerrilla group known for its decades-long campaign of violence against British rule in Northern Ireland.
But Sinn Fein, which was officially banned from appearing on Irish television until as recently as 1993, has changed. Its popularity has surged and this week's Irish referendum on the EU's fiscal treaty has put the party's success in the spotlight.
Sinn Fein has shared power in Northern Ireland for several years, but has had little success in the Irish Republic, despite efforts in working class areas such as O'Byrne's North Dublin suburb of Donaghmede.
Now, with an economic crisis threatening the fortunes of the political parties that dominated Ireland for generations, it is the second most popular party in the country.
O'Byrne, attending Sinn Fein's annual conference in Killarney last weekend, said young, educated members like his son, with no ties to the IRA's violence, are changing the face of the party.
"People feel rejuvenated. The young people in particular are seeing a brighter face to Sinn Fein and are more eager to come on board and shun the other parties," said the 57-year-old O'Byrne, a long time party member wearing a Dublin Gaelic football jersey.
"It's just blossoming. The people coming down the line, they have fresh ideas and for an old Republican like me, it's heart-warming. Fianna Fail, Labour and Fine Gael better watch out," he said, referring to Ireland's traditionally dominant parties.
While opinion polls show Thursday's vote is likely to carry, Ireland rejected two European treaties in 2001 and 2008, so a shock rebuke to the government cannot be ruled out.
Either way, as the only major party rallying against the German-led plan for stricter budget discipline, Sinn Fein's high-profile campaign has marked it out further from its rivals.
NO TO AUSTERITY
Riding an anti-austerity wave that has seen populist parties throughout Europe - from the far right to the hard left - benefit from a debt crisis, Sinn Fein's support hit a record 24 percent this week, according to an Irish Times/Ipsos MRBI poll.
That made it twice as popular as left wing rivals Labour, the junior coalition party it is targeting relentlessly. Sinn Fein now trails Prime Minister Enda Kenny's centre-right Fine Gael by a mere eight percentage points.
Two trends are particularly telling. When Ipsos MRBI ran a poll ahead of last year's election in which Sinn Fein captured 10 percent of the vote to more than triple its seats to a record 14, it was supported by just six percent of middle-class voters and seven percent of those over the age of 50.
According to Monday's poll, the level of support among these groups has risen to 16 percent and 22 percent respectively.
Its message is now tailored more to voters concerned about painful government-imposed austerity than the past of Northern Ireland's "Troubles".
Articulate party activists like Eoin O'Broin, the director of elections for this week's referendum on the fiscal treaty, are helping woo voters who once viewed Sinn Fein at best as irrelevant outsiders, and at worst as political pariahs.
Self-described as a "solidly south County Dublin middle class fellow", O'Broin was educated at the well-heeled Blackrock College, best known for producing ex-Prime Minister Eamon de Valera and Irish rugby captain Brian O'Driscoll.
Like many in Sinn Fein, he became involved in politics at university and was quickly promoted to overseeing key policy areas within the party even though he has yet to succeed in winning a seat at local or national level.
O'Broin believes it is this kind of talent spotting that has the potential to set Sinn Fein apart from the other parties.
"One of the features of the party, north and south, over the last decade is that the party creates space for young people to hold significant positions," he said.
"So it's not just that we have lots of young people and very talented young people but they see that the party takes them seriously and I think that encourages others to join."
"SHALLOW, CYNICAL AND WRONG"
However as political realities catch up with anti-austerity parties in Europe, Sinn Fein's policies - from rallying against an EU/IMF bailout to downplaying the risks of rejecting the fiscal treaty - have come under fire in the mainstream press.
The Irish Times ran an editorial this month entitled "Shallow, cynical and wrong" while under the headline of "Sinn Fein: smoke and mirrors", the Irish Independent wrote that its policies reflected core characteristics of "cynicism, hypocrisy and economic ignorance on a breathtaking scale."
While its membership has risen by 35 percent to nearly 7,000 since last year, it is still a way behind Fine Gael's 35,000.
To win a share of power it will also have to turn its popularity into seats in constituencies where it has never seriously competed before.
Like many political analysts, University College Dublin professor David Farrell believes it could take just two more electoral cycles for Sinn Fein to enter government, but that will depend on whether it can further widen its appeal.
"There's no doubt they are a force to be reckoned with and I think many of us would be surprised if they're not in government in some shape or form sometime in the next decade. But they're going have to make some hard choices if they want to go all the way to becoming one of the larger parties," Farrell said.
"Are they just going to try and become the strong working class party, go for broke on that one, or are they going to try and eat up some more centrist, middle class voters? To do that they will need to moderate their economic policies."
(Editing by Anna Willard)