The head of German Chancellor Angela Merkel's CDU voiced confidence ahead of a key meeting Monday that the party's top brass will back him as their chancellor candidate despite a challenge from his Bavarian counterpart.

CDU chief Armin Laschet and Markus Soeder, the head of the smaller Bavarian sister CSU party, both said Sunday they were open to leading the centre-right alliance into elections in September.

The CDU's senior leadership is meeting in Berlin on Monday to discuss the next steps as they look to chart a path towards a post-Merkel era against the backdrop of plummeting public support.

While the top brass is not expected to deliver a final decision on the chancellor candidate immediately, which way it leans would be a key sign of who the alliance would end up picking.

Asked in a TV interview with the Bild daily on Sunday evening if he had the support of the party heavyweights, Laschet replied: "I assume so."

"I know the views of many regional leaders, some of whom have already spoken publicly," he said. "But we will see tomorrow. I don't want to jump to conclusions."

Armin Laschet is a veteran Merkel ally
Armin Laschet is a veteran Merkel ally AFP / Tobias SCHWARZ

Long-time Merkel ally Laschet, 60, took over as CDU leader in January, and would normally be first choice to lead the parties into the elections on September 26, when Merkel will retire from politics after 16 years as chancellor.

But public support for the sister parties is tumbling over their recent handling of the coronavirus crisis, and some have called for Laschet to step aside in favour of the more charismatic Soeder, 54.

After months of speculation, Soeder confirmed his interest in being the parties' chancellor candidate on Sunday -- on the condition that he had the backing of the more powerful CDU.

As leaders of Germany's biggest federal states by population and area respectively, North-Rhine Westphalia premier Laschet and Bavarian chief Soeder have exchanged blows over their leadership in the pandemic.

Soeder consistently beats Laschet in popularity polls, with a recent survey by public broadcaster ARD showing that 54 percent of Germans thought Soeder would be a good chancellor candidate, compared to just 19 percent for Laschet.

However, German media reported that the CDU leadership will likely come out in favour of Laschet, in order not to destabilise the conservative alliance as a whole.

A final decision expected some time in the next two weeks, according to the reports.