German Chancellor Friedrich Merz cancelled a planned telephone call with President Trump on Wednesday, just hours after Trump publicly hailed a strong showing by Germany's Alternative for Germany (AfD) party in regional elections.

The cancellation came amid heightened tensions following the AfD's reported gains in key state votes. Trump had praised the outcome on social media and in remarks, describing it as a significant victory for the populist party against establishment policies.

Merz, who leads a coalition government that does not include AfD, had been expected to discuss bilateral issues including trade, NATO commitments, and European security with the U.S. president. No rescheduled time was immediately announced by either side.

The AfD has gained traction with voters in recent years by focusing on immigration control, economic concerns, and skepticism toward certain EU policies. Despite these gains, Germany's largest political parties doggedly continue a long-standing political agreement of maintaining the 'AfD firewall'. This informal consensus amongst the mainstream political groups refuses coalitions, formal cooperation, or any normalization of the AfD party or its members. They classify AfD as a 'right-wing extremist party' and aim to keep its members out of any power at the federal or state levels. With or without political allies, AfD's performance in the regional contests marked one of the party's strongest results to date.

Trump's comments highlighted the election results as evidence of shifting voter sentiment in Europe. The White House has not issued an official statement on the cancelled call.

Merz's office cited scheduling conflicts as the reason for the cancellation, without elaborating further on any connection to the election remarks. Diplomatic sources described the move as unusual given the longstanding U.S.-Germany alliance.

The move underscores ongoing divides in transatlantic relations over domestic European politics and the rise of populist movements. Both leaders are scheduled to attend upcoming international summits where further discussions may occur.