Mrs Merkel managed to broker a grand coalition deal with the left-wing Social Democrats after months of political uncertainty following the 2017 election in September.
Now as members from both parties vote to formalise the coalition agreement, some in the Chancellor’s party are demanding she do more to reach out to conservative citizens.
Their frustrations follow months of discomfort in the right wing ranks of the CDU, concerned by Mrs Merkel’s open door migration policy, greek eurozone bailout and the rise of far-right party Alternative for Deutschland (AFD).
Senior CDU official Daniel Guenther said: ”Sometimes the conservative element of the conservative bloc could be more prominent.”
Bavarian conservative Alexander Dobrindt said: “The conservative bloc must cover the spectrum from the centre to the democratic right.”
The vote on the coalition deal is expected to pass through both parties, allowing Mrs Merkel to continue into her fourth term as chancellor.
The two parties are expected to name their cabinet members in the coming days, hinting at the style of government Mrs Merkel will command.
It comes as the German Chancellor vows to bring reform to the European Union, branding her coalition as a “new dawn for Europe”.
Earlier this week she called for the EU to “prepare for change” ahead of 2019, when Britain leaves the bloc and Jean-Claude Juncker is replaced as EU president.
The German Chancellor, a strong anchor of Brussels, also expressed her desire for greater integration between member states in dealing with the migrant crisis, economic issues and security.
She said: “We want to have a Europe capable of action that is in solidarity and has self-confidence.
“To achieve this we must be ready to strengthen Europe where a European solution is better than a purely nationalist one.”
She added: “We can only continue to thrive in the future if EU thrives as well.”