The Christian Democratic Union (CDU) in Merkel's home region suffered a stinging backlash Sunday as the upstart opposition right-wing populist Alternative for Germany (AfD) party entered its 9th regional assembly since 2013.

But, the CDU could still govern as junior partner in a third-term coalition with Premier Erwin Sellering's center-left Social Democrats.

The AfD entered Mecklenburg-Western Pomerania's 71-seat Schwerin assembly Sunday after a campaign directed at Merkel's decision last year not to close Germany's border to refugees arriving in the country through Hungary and Austria.

AfD's Leif-Erik Holm (L) toasts his party's Schwerin entry

Merkel herself was in China Sunday attending the G20 summit, one year ahead of Germany's next federal election due in September 2017.

From Berlin, the CDU's federal general secretary, Peter Tauber, described Sunday's outcome as "bitter."

Hard campaign, but 'fantastic' SPD result

Incumbent Premier Erwin Sellering and his center-left Social Democrats, who have governed in coalition with the regional CDU for over 10 years, were returned with 30.5 percent, according to initial results that put turnout at 61 percent.

The SPD's Sellering could form his third coalition

That was nine percent more compared with the Schwerin assembly election in 2011.

Sellering said he was greatly concerned about the AfD's second placing, but went on to praise his SPD for its "fantastic" result in one of the "hardest electoral races" ever fought by the party.

Launched in 2013 on an anti-EU ticket, the AfD narrowly missed entry to Germany's Bundestag parliament in that year and until Sunday had secured opposition footholds in eight of Germany's 16 Bundesländer. It made its most recent gains in March during three other regional elections in central and southern Germany.

CDU relegated to 3rd

Sunday's results relegated leading CDU candidate Lorenz Caffier (pictured above with his wife) and his regional CDU conservatives to third place in the Schwerin assembly.

Exit polls put the opposition post-communist Left party on 12.5 percent, and the Greens, who campaigned to uphold "open society" on 5 percent, on the cusp of the 5 percent threshold common for parliamentary entry in Germany.

The far-right NPD exited the 71-seat parliament on 3.5 percent. It had previously held five seats, the only electoral regional foothold it had had across Germany.

The exit surveys also showed the pro-business liberal Free Democrats (FDP) on 3 percent, also below the threshold.

Sellering to renew coalition?

Prior to Sunday's election, there had been media speculation that Premier Sellering might try to form a three-way coalition, comprising his top-placed SPD and Caffier's bruised CDU, and possibly the opposition Greens - to clinch a governable majority beyond the 36-seat minimum needed.

A 'bitter' result for Caffier and his regional CDU

The initial results put the SPD on at least 24 seats, and Caffier's CDU on at least 15 seats - above the minimum required - with the Greens on four seats.

The populist AfD had 17 seats and the opposition Left 10 seats in the new parliament.

Polling 'without incident'

Sellering had campaigned on local issues, urging voters to focus on jobs creation in the wind turbine sector, decentralize integration of refugees and pension parity with Germany's western regions.

Sunday's election among 1.3 million voters in Germany's northeastern state proceeded in rain "without incident," according to its election commission, but was outweighed by an intense national gaze on the right-wing populist AfD.

Across the inland Masurian Lake District many voters lodged postal ballots.

Mecklenburg-Western Pomerania, with its regional capital Schwerin, was until German unification in 1990, part of communist East Germany.

Merkel, since then, has had her federal electorate in Stralsund, one of the Batlic Sea coastline's touristic ports.

ipj/jlw (dpa, AFD, Reuters)