Heinz-Christian Strache, the head of Austria's far-right party and the next vice-chancellor, dismisses his youthful dalliance with neo-Nazism as when he was "stupid, naive and young".

Now, three decades after German police detained him at a torch-lit protest by a group aping the Hitler Youth, Strache is the besuited, statesmanlike head of the Freedom Party (FPOe), rejecting all extremism.

But it remains to be seen how the man who in 2016 called German Chancellor Angela Merkel "the most dangerous woman in Europe", will act, and whether he can keep the party behind him.

When the former dental technician, brought up single-handedly by his mother in a lower-middle-class area of Vienna, took over the FPOe in 2005 aged 35, the movement was a mess.

Joerg Haider, its controversial but magnetic leader from 1986-2000, had broken off to form his own party, the movement torn apart by its last spell in government in the early 2000s.

But "HC", his striking blue eyes matching the party colours, restored its fortunes and in elections in October the FPOe won 26 percent -- more than double Alternative for Germany's score a month earlier.

This gave Strache, now cutting a mature figure in his new glasses, a ticket to enter talks to form a coalition with Sebastian Kurz's conservatives.

Those negotiations wrapped up late on Friday. Details of the new government's plans were due later Saturday.

- 'Fairness' -

When the FPOe last entered government in 2000 under Haider, there was uproar in Europe.

This time the reaction is likely to be muted, with Europe more inured to populists and the FPOe seen as having moderated.

Indeed, early in Strache's leadership, FPOe posters screamed "Daham statt Islam" ("Home not Islam") but over the years they became less shrill and more subtle.

In this year's campaign, the main messages were "Fairness" -- an elastic term encompassing everything from lower taxes to scrapping benefits for immigrants -- and opposition to "Islamisation".

Strache, now 48, has moved to clean up the party's image by suspending members for anti-Semitic behaviour, like a local councillor for a "Heil Hitler" salute in October.

But not everyone is convinced. In September a group remembering Nazi camp victims published a list of what it said were at least 60 anti-Semitic and racist incidents involving FPOe figures since 2013.

"If they really changed their ideology, it is a question they can only answer themselves," said analyst Alexandra Siegl. "I would say they changed their tactics and their strategies mainly."

- Immigration halt -

The FPOe manifesto vowed "no more immigration until further notice", pamphlets railed against criminal immigrants and it wants all integration efforts for refugees to stop -- because, so the logic goes, they are only here temporarily.

"No, Islam is not part of Austria," Strache, back in jeans and traditional loden jacket and accompanied by his model wife 20 years his junior, told a typical beer-swilling, flag-waving FPOe election rally.

"Strache is the counterweight to Angela Merkel whose 'welcome culture' is destroying Europe," one FPOe supporter told AFP, not wishing to give his name.

Strache appears ambivalent at best on Europe, calling Brussels a "bureaucratic monster", believing Britain will "probably be better off after Brexit" and saying EU sanctions on Russia must be lifted.

"Strache knows he has to act the statesman if the FPOe wants to get more than 20 percent," Nina Horaczek, an award-winning journalist who wrote a biography of Strache, told AFP before the election.

"But with their programme and all their talk of 'mass invasion' and the spreading of fear of an upcoming 'civil war' in our country, it's obvious they remain radical."

- Stolen thunder -

Strache has also made deft use of the internet, with more Facebook "fans" than any other party leader, and until earlier this year he was on a roll, dreaming perhaps of becoming chancellor.

In December 2016, the FPOe's Norbert Hofer came close to being elected Europe's first far-right president since 1945 and the party was topping national polls.

But in May Kurz, just 31, took over the centre-right People's Party (OeVP) and leapfrogged the FPOe into first place in the polls -- thanks partly to moving rightwards and stealing many of Strache's policies.

Strache, poking fun at "late bloomer" Kurz and presenting himself as the "visionary", struggled to recover. But at least now he has brought his party into government -- for how long time will tell.