German magazine "Spiegel" reported on Saturday that next year's election could see the Christian Social Union (CSU) campaigning even more independently than in 2013.

At a meeting of the CSU Strategy Commission for next year's election, Horst Seehofer, chairman of the CSU and Minister President of Bavaria, reportedly said that if the CDU fails to deal with the growing popularity of the right-wing Alternative for Germany (AfD), then the CSU must, at a pinch, launch its own election campaign.

The populist AfD, which was initially founded as an anti-bailout alliance in 2013, is now represented in eight of Germany's 16 state parliaments. Even at the national level, the party has made strong gains, with opinion polls suggesting that they now hold between 12 and 14 percent of the vote.

According to German newspaper "Bild," Merkel told party allies on Monday that more needed to be done to win over conservative voters to prevent even more of them jumping ship to support the AfD. The CDU must "grapple with other opinions, including those of the AfD, without foam at the mouth and without blanket prejudice," Merkel said.

Differences previously 'unimaginable'

In the event that the CSU campaigns indepependently for the 2017 chancellery, Seehofer would run at the top of the national candidates,"Spiegel" reported.

"Then it must be made clear to voters that they're not choosing Merkel, but the CSU," Seehofer said.

Transport Minister Alexander Dobrindt (CSU) told "Spiegel" that it was unclear whether there would be a common election platform of both parties.

"I'd never have imagined that the CDU and CSU could even think so differently about such a central topic as we've seen on the issue of refugees," he added.

In light of the unprecedented influx of some 1.1 million refugees to Germany last year, tensions between the two sister parties have dramatically increased in recent months, with Seehofer - whose state lies on the border with Austria and thus at the heart of Germany's refugee crisis - publicly criticizing Merkel's open-door policy on countless occasions.

The CSU has repeatedly called on Merkel to restrict the number of new refugee arrivals this year to 200,000. But with the chancellor strongly opposed to limiting the amount of people able to seek asylum in Germany, tensions remain high.

'Bavaria plan'

The CSU already stressed their independence in the 2013 chancellery election campaign. Although there was a common election manifesto, the CSU still campaigned for the national, as well as the state election with a "Bavaria plan."

Included in the plan were points which the CSU was unable to include in the joint manifesto due to opposition from the CDU, such as the introduction of a car toll fee for foreigners and nationwide referendums on fundamental EU decisions.