BERLIN (Reuters) - German Chancellor Angela Merkel's Bavarian ally Horst Seehofer suffered a setback on Thursday when his spokesman was forced to resign over allegations he tried to manipulate TV coverage of an opposition party.
The political turmoil in Bavaria, which has been ruled by the CSU, the Bavarian sister party to Merkel's Christian Democrats for the last 55 years, could hurt Seehofer's chances of re-election as premier next year and damage Merkel's campaign to win a third term.
Seehofer will fight a September 2013 regional election against popular Munich mayor Christian Ude, nominated on Sunday by the centre-left opposition Social Democrats (SPD).
A poor result for conservatives in Bavaria could hurt Merkel in her election, expected to follow a week or two later.
Seehofer abruptly cancelled appointments on Thursday to be in Munich as the scandal dominated German media bulletins. He said his aide Hans Michael Strepp had to step down because of a lack of clarity over whether he had tried to influence coverage on the German public TV network ZDF.
"If the issue with ZDF can't be clarified, it was a necessary step and the right step," Seehofer told reporters.
ZDF had said that Strepp urged the network to ignore Ude's nomination in its Sunday evening broadcast. Strepp denied it but offered his resignation on Thursday as the scandal grew.
"The spokesman for the CSU tried in various ways to influence ZDF's coverage of another party," ZDF editor-in-chief Peter Frey said.
The conservative stronghold of Bavaria will be particularly important for Merkel in next year's federal election. In the last two years her party has lost control of North Rhine-Westphalia, Germany's most populous state, as well as the traditionally conservative-ruled Baden-Wuerttemberg and Schleswig-Holstein.
Some polls have shown the SPD and its Green allies could knock the CSU out of power in Bavaria, though a poll last week showed the CSU had a comfortable lead.
Opposition political leaders jumped on Strepp's resignation.
"It's hardly conceivable that a party spokesman would make a phone call like that without approval from higher up," said Thomas Oppermann, a leader in Berlin for the SPD.
Even a leader of the Free Democrats (FDP), coalition partners to Merkel in Berlin and Seehofer in Munich, called it unsettling. "It's a serious threat to freedom of broadcasters," said Burkhardt Mueller-Soenksen, a media policy expert in the FDP in the Berlin parliament.
Earlier this year President Christian Wulff tried to stop a newspaper publishing a story about a loan and later resigned.
(Reporting by Irene Preisinger; Writing by Michelle Martin; editing by Erik Kirschbaum and Rosalind Russell)