Goldman alum and former US ambassador warns Trump: You can't govern alone

Heyman: Canada is the most important relationship we have

President Donald Trump should not ignore the vast "knowledge base" embedded in the various federal agencies when crafting his foreign policy agenda, former U.S. Ambassador to Canada Bruce Heyman told CNBC on Monday.

"The capabilities and qualities of the people that I interacted with at the embassy and the highest levels of the U.S. government are as good as any people that I've worked with anywhere in the world," Heyman said on "Squawk Box." That's high praise from a diplomat who served three years in the Obama administration and for 33 years at Goldman Sachs.

Trump has leaned on Goldman alums in key administration posts. Ex-Goldman banker Steven Mnuchin is expected to be confirmed as Treasury secretary Monday evening. Gary Cohn, who left his No. 2 executive spot at Goldman, serves as director of the White House National Economic Council.

Heyman said it appears Trump did not engage in the large part of the infrastructure of the U.S. government before releasing some of his early executive orders. That's been "causing him some difficulties" recently, the former ambassador added.

The president has suffered two defeats in court over his executive order temporarily banning entry into the U.S. by travelers from seven Muslim-majority countries that have raised concerns about being hotbeds for terrorism.

"The president should utilize the knowledge base that we have in the various departments," Heyman said. "This is a resource for the White House to tap into. I think it's a mistake not to tap into that."