Trump's tweets 'are hurting him,' says former McDonald's CEO

The former CEO of McDonald's callsU.S. PresidentDonald Trump "childish" and says he should "quit tweeting."

"His tweets are hurting him," said Ed Rensi, who served as president and chief executive officer of McDonald's from 1991 to 1997 and still sits on its board.

You can't be a bully. You don't bully the CEO of Merck.- Ed Rensi

Rensi was referring in part to Trump's comment aimed at Merck CEO Ken Frazier, who resigned Monday morning from the president's American Manufacturing Council over Trump's failure to reject "expressions of hatred, bigotry and group supremacy."

Frazier, who is black, representspart of thegrowing backlash from business leaders in the wake of Trump's delayed and half-hearted reaction to the white nationalist rally this past weekend in Virginia that left three people dead and dozens injured.

Trump shot back at Frazier hours before he finally condemned the racist violence of the weekend in strong terms, which he tacked on to a speech about trade deals and the economy.

In an interview with CBC's On The Money on Monday, Rensi denounced what he called the president's "bad behaviour."

"I think it was childish and unprofessional and beneath the dignity of a guy holding that office. Shame on him, he shouldn't behave that way," Rensi told host Peter Armstrong.

"And you can't be a bully. You don't bully the CEO of Merck."

'He's a lousy politician'

Rensi saidhe voted for Trumpand still supports him.

"I think fundamentally he's a good guy.I think he's a good businessman.I think he's a lousy politician," Rensi said.

"He's inarticulate sometimes, he's bullheaded, he's stubborn a lot of times he needs to calm down, listen to the people around him and start to value their opinion and start taking considered conversation and not just blurting out whatever jumps into his brain," Rensi said."And Ihope he grows up and understands what's going on."

• Trump attacks Merck exec for quitting council over Charlottesville
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• There is no moral equivalency when it comes to neo-Nazi white supremacy: Opinion

Other CEOs have left White House advisory councils over disagreements with Trump's policy: former Uber CEO Travis Kalanick;Tesla and SpaceX mogul Elon Musk;and Robert Iger, chairman of the Walt Disney Company.

For those who remain, Rensi said, "They need to talk to Trump in a very clear direct manner and tell him point-blank that he is to think, listen and talk carefully.

"No man in a leadership position, or no woman, is any better than his willingness to trust his subordinates and the people that are trying to help him."

Saturday's white nationalist rally turned deadly when a driver plowed his car into a crowd of anti-racism protesters, killing 32-year-old Heather Heyer. Two state troopers monitoring the rally died after their helicopter crashed.

James Alex Fields Jr., 20, of Ohio, is charged with second-degree murder, three counts of malicious wounding and one count related to leaving the scene.

Republicans and Democrats alike denounced the president's initial response to the violence Saturday, in which he condemned "in the strongest possible terms this egregious display of hatred, bigotry and violence on many sideson many sides," repeating the phrase for emphasis.