Yet the departure of Cohn,a free-trade oriented Democrat who fended off a number of nationalist-minded policies during his year in the Trump administration,could have a ripple effect on the President's economic decisions and on the financial sector.

Even the mere threat,last August,that Cohn might leave sent the financial markets tumbling.

And his planned exit comes as Trump is making a more aggressive return to the nationalist policies that helped sweep him into office as the 2018 midterm elections approach.

Trump's announcement last week that he would levy tariffs on aluminum and steel imports was the most immediate catalyst for Cohn's departure,according to people familiar with his thinking. Cohn,a longtime proponent of free trade,believed the decision could jeopardise economic growth.