BERLIN, April 26 (Xinhua) -- The German government expressed concern on Thursday that a solution to the trade conflict unleashed by U.S. President Donald Trump remains elusive as Chancellor Angela Merkel (CDU) is preparing her visit to the United States.

German media cited government sources warning that an extension of the European Union's (EU) current exclusion from new U.S. tariffs on aluminum and steel imports was unlikely be achieved prior to the lapse of the current agreement on May 1. Merkel is set to travel to the U.S. on Thursday evening and is widely expected to launch a last-ditch attempt there to convince President Trump to reverse his protectionist stance.

Merkel has repeatedly emphasized that the partnership between Washington and Berlin remains central to German foreign policy despite some disagreements between Trump and her. However, the chancellor is still anticipated to reiterate Europe's united stance in opposition to Trump's "America First" doctrine.

Speaking to the newspaper "Koelner Stadt-Anzeiger" on Thursday, Peter Beyer, the coordinator for transatlantic cooperation in the German Foreign Office highlighted that Merkel was most likely to succeed in altering Trump's stance on trade by working together with French President Emmanuel Macron. "Macron is closer to Trump on a personal level" Beyer said. The French president has just concluded his own multi-day trip to Washington.

The economic council of the Christian Democratic Union (CDU) cautioned that the upcoming meeting between Merkel and Trump would set the trajectory for future trade relations between the U.S. and Europe. Council secretary Wolfgang Steiger consequently urged Merkel to demand a permanent exclusion of the EU from tariffs once again.

Aside from trade, the future of the Iran nuclear agreement is another subject which Merkel will raise in Washington.

Germany and Russia have both rejected suggestions by Trump that the existing agreement could be renegotiated.

The U.S. president is threatening to withdraw from the landmark deal entirely by May 21 unless its scope is expanded significantly.

Commenting on the issue, Greens (Gruene) foreign policy spokesperson Juergen Trittin called on Merkel to remain firm on the issue during her visit. Trittin told press on Thursday that "flattery will not result in American concessions." Instead, the chancellor would have to "speak a language that Trump understands", namely that of "cost-benefit calculus."

Nevertheless, a poll published by the "Funke" media on Thursday found that most Germans have little faith in an improvement of diplomatic relations between Berlin and Washington. More than two thirds of respondents (68.1 percent) indicated that relations were likely to deteriorate further despite Merkel's effort of persuasion.