Angela Merkel's arch-conservative sister party in Bavaria has crashed to its worst result for 68 years in state elections, according to preliminary results, piling further pressure on the German Chancellor's beleaguered coalition.

The Christian Social Union (CSU), which has ruled the wealthy southern state almost single-handedly since the 1960s, is projected to lose its absolute majority after dropping more than 10 percentage points to register around 37 per cent of the vote.

The anti-immigrant Alternative for Germany (AfD) won its first seats in the Bavarian parliament, scoring more than 10 per cent in spite of the CSU's efforts to fend it off with a hardline stance on immigration and law and order.

The Social Democrats, who are Merkel's coalition partners in Berlin, also slumped to a historic low with barely 10 per cent, as the Greens doubled their vote share to leapfrog them in second.

Members of the Christian Social Union await the results in Munich, as the ruling party slumped to a historic low in state elections in a result which piles further pressure on Angela Merkel

Alice Weidel and Katrin Ebner-Steiner of the anti-immigration party Alternative for Germany (AfD) react after the announcement of the first exit polls in Bavaria on Sunday evening

Green Party leaders Robert Habeck, centre, and Anton Hofreiter, right, react to the exit polls after their party surged into second place in Bavaria's state elections on Sunday

The results signalled a failure for the CSU's efforts to maintain its dominant position in the state in the face of the AfD's hardline rhetoric.

'Of course today is not an easy day for the CSU. We did not achieve a good result,' CSU state leader Markus Soeder told a gathering of his party.

'We accept the result with humility,' he said, adding that the CSU - which will need a coalition partner - nonetheless wanted to form a stable government as soon as possible.

Since Germany's mass migrant influx of 2015, the CSU has hardened its folksy beer hall brand with an increasingly aggressive anti-immigration and law and order rhetoric intended to stop its voters drifting to the AfD.

Bavaria became Germany's frontline state for a mass influx of mostly Muslim refugees and migrants, half of them from Syria, Iraq and Afghanistan.

During the campaign the CSU has promoted crucifixes in school classrooms and opposed Islamic veils in public.

At the national level, its Interior Minister Horst Seehofer became Merkel's harshest internal critic, echoing the AfD's rhetoric about the more than one million refugee and migrant arrivals.

The poll result on Sunday showed that the tactic - and Seehofer's brinkmanship in Berlin, including threats to resign - have backfired badly.

Following Sunday's results Seehofer, 69, said: 'It was not a nice day for us', but both he and Soeder have indicated they will stay in their jobs.

AfD chair Alice Weidel (left) drinks beer with fellow party members after their party entered the Bavarian state parliament for the first time and was projected to reach over 10 per cent

Leader of the Christian Social Union (CSU) Horst Seehofer - a rival of the Bavarian state premier - reacts to the first exit poll in the state elections on Sunday

Top candidate of the Green party in Bavaria Ludwig Hartmann and co-leader of the Greens Robert Habeck celebrate with their supporters following a surge in support

Bavarian state premier Markus Soeder gives a TV interview to journalist Bettina Schausten

Soeder has recently pointed to turbulent 'Berlin politics' for the CSU's poor outlook, suggesting he is likely to point the blame at longtime rival Seehofer.

The exit polls leave them on course for their worst result in a Bavarian state election since 1950, while the AfD - which had never previously competed in one - are now represented in 15 of Germany's 16 state parliaments.

Profiting from the refugee backlash, the AfD took millions of votes in last year's general election to weaken all the mainstream parties.

The Free Voters, a protest party who could form a coalition with the CSU, were projected to come third in Sunday's Bavarian election with 11.5 per cent.

The Greens, who are also regarded as a possible coalition partner, more than doubled their share and attracted support from more liberal CSU voters.

'If you copy the far right, you lose,' said the Greens' national co-leader Annalena Baerbock.

The coalition arithmetic may hinge on whether the FDP clears the five per cent threshold to be eligible for seats, which was not certain from early exit polls.

For Merkel, who was largely spurned by the CSU during the campaign, the results will heighten tensions in her fragile coalition.

State premier Markus Soeder, left, shakes hands with Hubert Aiwanger of the Free Voters, who were projected to come third and could form a coalition with the weakened CSU

Markus Soeder (second right) speaks on German television after the results were announced

Supporters of the Social Democratic Party (SPD) look dejected as they watch exit polls at the Bavarian state parliament in Munich. Their party slumped to a historic low in the election

A screen shows the first projections according to German broadcaster ARD, with the CSU remaining in first place but losing its absolute majority with its lowest share for 68 years

Members of the Christian Social Union Party (CSU) react after the announcement of the first exit polls in the Bavarian state elections which saw the party suffer record losses

She forged the 'grand coalition' between her CDU - allied to the CSU - and the reluctant SPD after months of talks following the last nationwide election in 2017.

Across Germany, support for the CDU-CSU conservative union has dropped to an all-time low of 26 percent, according to a recent poll.

The 'bitter' losses in Bavaria reflect voter dismay over recent coalition infighting in Berlin, conceded the CDU's general secretary Annegret Kramp-Karrenbauer.

SPD leader Andrea Nahles conceded a 'bad result for the SPD ... and for all mainstream parties' that she said was partially due to 'the bad performance of the grand coalition in Berlin'.

For the SPD, who are projected to come fifth, the result is a further humiliation after they slumped to barely 20 per cent of the vote at last year's federal election.

A poll by public broadcaster ARD showed that most voters blame Berlin-based politicians for the CSU's poor performance.



Angela Merkel's arch-conservative CSU allies have suffered heavy losses in Bavaria today in a result which will pile further pressure on her coalition. She is pictured in Berlin last week

German Interior Minister Horst Seehofer attends a television debate to comment on the results of the the regional elections. He has said he will stay on as leader of the CSU

Volunteers count the votes in Bavaria's state elections in Munich on Sunday evening

CSU state premier Markus Soeder (pictured), 51, as he cast his ballot amid high turnout from the 9.5 million eligible voters. His party slumped to its worst result for 68 years

Electoral officials sort ballot papers in Munich after the conclusion of voting in Bavaria

People dressed in typical Bavarian clothes cast their votes for regional elections in Bavaria at a polling station in Neukirchen, southern Germany

While 56 per cent saw Seehofer as the chief culprit, 24 per cent pointed to Merkel, followed by Soeder at eight per cent.

Seehofer has already declared he intends to stay on and 'complete my mission' as interior minister.

Another breakdown suggested that the Greens had come first in towns and cities with more than 100,000 inhabitants. Early results showed them in the lead in Munich, the state's largest city.

Early results suggested the turnout, at 72 per cent, was the highest in a Bavarian state election since 1982.

It comes just two weeks before another dangerous vote, in the central state of Hesse, and ahead of a December Christian Democrats (CDU) congress where Merkel plans to run again as party chief.

'Merkel knows, no matter the election outcome, uncomfortable times lie ahead,' said the Sueddeutsche newspaper, predicting that a 'humiliated CSU will be looking for culprits ... and the name Angela Merkel will certainly fall'.

Merkel has been largely absent from the CSU election campaign, which in its final rally on Friday invited instead Austria's right-wing Chancellor Sebastian Kurz.