Voters in the eastern German state of Thuringia boosted the far-right Alternative for Germany (AfD) in regional elections on Sunday, according to preliminary results, but the Left party will remain the dominant political force in the state.

With all districts reporting, results showed the Left party winning 31% of votes in the state that was once part of the communist former East Germany.

The far-right AfD party snagged 23.4% of the vote, making it the second-largest party in the assembly — and pushing German Chancellor Angela Merkel's CDU party into third place with 21.8%.

The turnout for the Thuringia polls was unusually high. Nearly 65% of the state's 1.7 million voters cast their ballots, compared to less than 53% five years ago. Postal votes were not included in the statistics.

Although the results indicate a historic result for the Left party, the makeup of the future state government remains uncertain.

Read more: Germany's AfD aims at a forgotten demographic

For the first time, the Left party became the strongest party in a German state

AfD confident after exit polls

The populist AfD party in Thuringia is led by Björn Höcke, who often draws attention to himself with firebrand statements. Höcke has notably criticized the Holocaust memorial in Berlin, describing it as a "memorial of shame" and called for a "reversal" of Germany's culture of remembrance.

After the exit polls were announced, Höcke said the voters wanted another change comparable to the fall of the Berlin wall.

"This is a clear sign that a large part of Thuringia says: This can't go on," he told public broadcaster ARD. "We need renewal — this should be taken seriously."

Höcke added that his party would win an outright majority in the next election cycle.

The AfD boasts strong support in other eastern states, winning 27.5% in Saxony-Anhalt and 23.5% in Brandenburg in September. However, other political parties have so far refused to form coalitions with the populist group at a state or national level.

The AfD's co-leader Alexander Gauland, who attended the celebrations in Thuringia, told the broadcaster Phoenix that Höcke "is not pulling the party to the right."

"He is the center of the party," Gauland said of Höcke.

Watch video 00:29 Höcke: 'A result that says yes to a new, vibrant democracy'

Losing the Left's razor-thin majority?

Thuringia is currently the only German state to have a premier with the Left party. The popular Premier Bodo Ramelow rules in coalition with the center-left SPD and the pro-environment Greens.

"I see myself clearly strengthened," he told ARD. "My party clearly has the mandate to govern, and I will take it up."

Support for the SPD, however, slid down to 8.2%, losing some 4% compared to its 2014 result. Although the Greens suffered a smaller loss, and are now hovering around 5.2%, the current ruling coalition is due to lose its majority.

Forming Thuringia's next coalition government is set to be extremely difficult.

In order to reach a majority in the state's 90-seat parliament, there are currently three difficult and highly unlikely options on the table.

The Left, SPD and Greens could remain in power, but they would have to bring the pro-business Free Democrats (FDP) on board as well. Preliminary results put support for the FDP at 5% — just enough for the party to clear the threshold to enter parliament.

On Sunday evening, FDP leader Christian Lindner firmly rejected the possibility of entering into a coalition with either the Left party or the AfD, saying that "both parties want to change the economic and societal order in Germany."

It would also technically be possible for the Left party to reach a majority if it partners up with either the CDU or the AfD, although the CDU ruled out working with the Left party prior to the election and a coalition between the Left and the far-right is even more unlikely.

Ramelow is the first and currently the only state premier from the Left party

'Bitter result'

Merkel's CDU suffered the greatest loss during Sunday's election, dropping down 11% from 2014. The result is a heavy blow for the center-right party and a win for the AfD, which had eyed the CDU's disillusioned supporters.

Projections showed that the AfD pulled the most support from voters who did not participate in Thuringia's last state election, followed by voters who previously voted for the CDU, according to initial projections.

The CDU's top candidate, Mike Mohring, lamented the "bitter result" of centrist parties not being able to form a majority.

Senior SPD member Olaf Scholz said he was concerned by the outcome and the AfD's surge.

"The result is, of course, not pretty," he told ARD.

rs, dj/aw ( dpa, Reuters, AP)

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