German eurosceptics go mainstream in threat to Merkel

* Alliance with Cameron's Tories helps AfD shed populist tag

* One year old party talks less about euro, more about values

* AfD expected to do well in looming eastern state elections

* Merkel's CDU tries to contain debate on cooperation

By Noah Barkin and Stephen Brown

BERLIN, June 15 (Reuters) - The Alternative for Germany (AfD) failed to make as big a splash in European elections last month as its eurosceptic counterparts in France and Britain. But that may be about to change.

Less than a month after the vote, the party formed last year by a group of renegade academics is on track to establish itself as a permanent force in German politics and a long-term headache for Chancellor Angela Merkel and her Christian Democrats (CDU).

The admission last week of the AfD into British Prime Minister David Cameron's conservative faction in the European Parliament has given the party a dose of credibility and its leaders a boost in their drive to distance the AfD from the populist, anti-immigrant movements of France's Marine Le Pen and Geert Wilders of the Netherlands.

After a professionally run EU campaign in which the party spoke less about its signature issue, the euro, and more about conservative German values, pollsters say the AfD is being seen by a growing number of voters as a legitimate, democratic party to the right of the CDU, and less like a flash in the pan.

Ahead of three regional elections in eastern Germany which are likely to vault the AfD into state assemblies for the first time, their rise is unsettling members of the CDU, with some now suggesting their party consider cooperating with the upstarts they had hoped would fade away.

"The AfD is establishing itself as a national conservative party, the kind that couldn't emerge after 1949 (when West Germany was founded) but has a tradition in pre-war Germany," said Ulrike Guerot of the Open Society Initiative for Europe.

Its core supporters are not rabid xenophobes, as Germany's mainstream parties have seemed to suggest, but church-going traditionalists who believe in conservative family values, are deeply worried about the loose policies of the European Central Bank (ECB) and want Germany to cure its own ills rather than help its euro partners.

"Until now these voters had stuck with the CDU. But under Merkel the CDU has lost much of its conservative flavour," Guerot said.

BROADER MESSAGE

In the German federal election last September, the AfD fell just shy of the 5 percent threshold needed to enter the Bundestag lower house of parliament.

Some experts predicted the party would wither away like the once trendy Pirates party, and in the months after the German vote that looked like a good bet. At the turn of the year, media reports on the AfD described a party in crisis, beset by infighting and struggling to stem an exodus of members.