(Bloomberg) -- German authorities have classified the Alternative for Germany chapter in the state of Saxony as right—wing extremist, the third regional branch of the party in the former communist east to be categorized as such.

The decision, which follows similar moves in the states of Thuringia and Saxony-Anhalt, paves the way for heightened surveillance. Known by its German acronym AfD, it has the strongest support of all parties in Saxony with 35%, according to an opinion poll published at the end of August. A regional election will be held in September.

At the national level, the anti-immigrant group has tapped into voter discontent on issues such as the government’s handling of rising numbers of refugees to climb to second place in the polls behind the main opposition conservatives.

Dirk-Martin Christian, president of Saxony’s domestic intelligence agency, said Friday that four years of “intensive investigation,” during which the agency collected a large number of statements from AfD officials, “prove beyond doubt that the local AfD state association is pursuing anti-constitutional goals.”

“Right-wing extremist statements by leading functionaries and elected representatives are acknowledged internally without the state party publicly distancing itself or at least critically confronting them,” Christian said in an emailed statement. “There is no longer any doubt about the right-wing extremist orientation of the AfD Saxony.”

The new designation means that legal hurdles are lower for the authorities to deploy measures like tapping telephone calls or using informants to monitor potential illegal activity.

Germany’s mainstream political parties have mostly refused to cooperate with the AfD at any level of government, though that stance is becoming increasingly difficult to maintain with the party commanding more than 30% of the vote across eastern Germany and in excess of 20% nationally, according to polls. 

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In September, senior members of Chancellor Olaf Scholz’s Social Democrats accused opposition lawmakers in Thuringia of breaking a political taboo after they joined up with the AfD to force a tax cut through the regional parliament.

The Thuringia CDU and FDP were poised to vote again with the AfD on Friday as part of an effort to block the installation of wind turbines in wooded areas, public broadcaster MDR reported.

The election in Saxony is scheduled to take place on Sept. 1, followed by ballots in the eastern regions of Brandenburg on Sept. 22 and Thuringia at some point in the fall. Before that, a European Parliament election will be held on June 9, and municipal votes will happen in Brandenburg, Saxony and Saxony-Anhalt.

--With assistance from Michael Nienaber.

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