By Erik Kirschbaum
BERLIN (Reuters) - A battle for control of the German Eurosceptic upstart Alternative for Germany (AfD) exposed deep ideological rifts at the weekend within a party that has been stealing votes from Chancellor Angela Merkel's conservatives.
Merkel had chosen to ignore rather than directly challenge the AfD, which has soared from nowhere to around 7 percent in national opinion polls in less than two years, in the hope that it would burn itself out.
That prospect appeared more realistic with the publication of ill-tempered letters from AfD leaders at the weekend ahead of a congress on Jan. 31 at which founder Bernd Lucke is seeking to take sole control of the party.
The bid triggered open conflict with his two co-chairs, Frauke Petry and Konrad Adam, who want to broaden the AfD's appeal for far-right voters with an anti-immigrant stance. A Lucke backer, Hans-Olaf Henkel, blasted Adam on Sunday as "scurrilous".
Adam, Petry and three other AfD leaders had sent a letter to Lucke denouncing his "despot-like style of leadership".
"You've completely lost the plot and don't even realise it," Henkel, former head of the BDI industry confederation, told Adam. "You seem consumed by disappointment over your loss of importance in the party. You're light years away from Lucke. You make yourself look ridiculous."
The AfD scored around 10 percent in three regional state elections in east Germany last year with its crusade against euro zone bailouts, siphoning votes away from Merkel and her erstwhile Free Democrat (FDP) allies and making it more difficult for her conservatives to form governments.
But the bitter public arguments over their future course mean that the next regional election, on Feb. 15 in Hamburg, will be a major test of the AfD's durability.
"It's incredible to see them squabbling like kindergarten children," said Thomas Jaeger, a Cologne University political scientist. "Merkel said all along it's better to ignore them, and it's good news for her that they're tearing themselves apart."
(Writing by Erik Kirschbaum; Editing by Kevin Liffey)