By Paul Carrel and Tom Käckenhoff
BERLIN/DUESSELDORF, Germany (Reuters) - Germany's Christian Democrats were set for an election win in the state of North Rhine-Westphalia on Sunday, an exit poll showed, and state Premier Armin Laschet took confidence from the victory as he seeks to succeed Chancellor Angela Merkel.
Laschet, who is positioning himself as the continuity candidate to succeed Merkel, was aiming to increase the Christian Democrats' lead over rivals in the local elections to boost his standing ahead of a December party leadership showdown.
He achieved that by widening his party's margin over the left-leaning Social Democrats (SPD), and claimed victory despite the Christian Democrats' (CDU) share of the vote dipping.
A forecast for broadcaster WDR based on exit polls showed support for the CDU slipping 1.5 percentage points from the last local elections in 2014 to 36.0%.
The SPD came second with 23.5%, down 7.9 points, and the Greens third with 19.0%, up 7.3 points.
"This is the biggest election we have in Germany in 2020. Fourteen million people were called to the ballot boxes and we can say today: The CDU has won these elections," Laschet told supporters in the evening.
"Now probably everyone in the CDU understands that the middle course is the right one," he said.
The elections, in which voters chose local town councillors, were the first in Germany since the coronavirus hit the country. Voter turnout was nonetheless up 1.5 points at 51.5% compared with 2014, WDR said.
The liberal Free Democrats (FDP) polled 4.5%, the far-left Linke 4.0% and the far-right Alternative for Germany (AfD) 6.0%.
Polls showed that voters gave Laschet a poor rating for his management of the coronavirus pandemic in Germany's most-populous state.
The elections came as the CDU looks ahead to a congress in December when it must choose a new leader.
The new CDU chairman will be in the pole position to be the party's chancellor candidate, although in theory the leader of its Bavarian sister party, the Christian Social Union (CSU), could run as the candidate for their alliance, dubbed "the Union".
Merkel, in power since 2005, has said she will not seek re-election in federal elections due by October next year.
An opinion poll published on Sunday suggested Laschet had his work cut out for him. Most Germans - 31% - favour CSU Chairman Markus Soeder as the Union candidate for chancellor, the Sept. 9-10 survey of 1,013 voters by pollster Kantar for Bild am Sonntag showed.
Health Minister Jens Spahn came second, on 14%, followed by erstwhile Merkel rival Friedrich Merz, at 13%, and then Laschet on 8%. Among Union supporters, support for Soeder hit 46%.
Soeder, who has so far played down any interest in running for chancellor, told Saturday's Frankfurter Allgemeine Zeitung: "My place is in Bavaria."
No chancellor has ever come from the CSU.
(Reporting by Paul Carrel and Tom Käckenhoff; Writing by Paul Carrel; Editing by Emelia Sithole-Matarise, Hugh Lawson and Peter Cooney)