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Two more business leaders left one of President Donald Trump's manufacturing advisory councils Tuesday, including the head of the nation's largest labor federation.

AFL-CIO President Richard Trumka and Alliance for American Manufacturing head Scott Paul joined the chief executives of Merck, Intel and Under Armour, who left Monday in the wake of Trump's initial remarks following the racially charged violence in Charlottesville, Virginia.

Scott Paul, head of the Alliance for American Manufacturing. Alliance for American Manufacturing

Trump had unleashed a Twitter blast earlier in the day against the CEOs who left his Manufacturing Council and boasted that he would easily replace them.

"For every CEO that drops out of the Manufacturing Council, I have many to take their place. Grandstanders should not have gone on," he tweeted Tuesday morning, adding at the end, "JOBS!"

Trumka announced he was leaving the council Tuesday afternoon after Trump, during a press conference from Trump Tower in Manhattan, blamed the Charlottesville bloodshed on "two sides."

I cannot sit on a council for a President that tolerates bigotry and domestic terrorism; I resign, effective immediately. pic.twitter.com/ip6F2nsoog — Richard L. Trumka (@RichardTrumka) August 15, 2017

Walmart's CEO, Doug McMillon, a member of a Trump advisory council on economic development, added his rebuke to the chorus.

“As we watched the events and the response from President Trump over the weekend, we too felt that he missed a critical opportunity to help bring our country together by unequivocally rejecting the appalling actions of white supremacists," wrote McMillon in an internal employee memo that was also posted to a public Walmart website. The Walmart executive, however, isn't leaving the board.

Business to Business

The defection by a set of influential corporate leaders Trump personally picked for guidance is the latest snub for a president who touted his “Art of the Deal” business acumen as a fresh perspective on the problems in which the overly politicized “swamp” of Washington, D.C., found itself mired.

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But the president’s relationship with corporate America has increasingly shown signs of fracture, as business leaders struggle to please customers and investors who oppose Trump's hard-line policies and question his effectiveness, and those who applaud his strong-arm techniques.

Now this wave of exits threatens to to become a "tsunami," Richard Levick, CEO of the Washington, D.C.-based LEVICK crisis management and public relations firm, told NBC News.

"There is a greater risk for CEOs staying on this council than leaving. This is a president who until this past weekend only dog whistled to the far right," he said. "Now, CEOs cannot remain and face their customers or shareholders or anyone they may want to face and say they care about diversity."

By staying, the CEOs theoretically got one-on-one face time with Trump and the opportunity to make the case for their own business and political interests. And of course there's the prestige factor. Or they may see serving the president, whatever they think of him, as their patriotic duty, as Chase CEO Jamie Dimon has said.

"There's always an upside to participating in a White House council," said Elaine Kamarck, a senior fellow at the left-leaning Brookings Institution think tank. "You get access to decision makers, access to the President. These are coveted slots that people like because they can try and get their point of view across about things that affect their industry."

In the Firing Line

One other mitigating factor may be that a single tweet from the president directed at a company can temporarily ding stock prices and inspire a magnifying storm of angry tweets from his followers, along with unwanted follow-up news coverage.

After Merck CEO Ken Frazier announced on Monday his decision to leave, the president immediately singled him out in a tweet, saying, "Now that Ken Frazier of Merck Pharma has resigned from President's Manufacturing Council, he will have more time to LOWER RIPOFF DRUG PRICES!"

While it's not that unusual, historically speaking, for C-suite executives to clash with their commander-in-chief and for words to get heated, political observers say this time is different.

In 1907, trust-busting and pro-regulation President Theodore Roosevelt spoke against overreaching businesses, calling them "malefactors of great wealth." After Roosevelt's term ended and he was on an African hunting safari, banking magnate J.P. Morgan quipped, “Let every lion do his duty.”

Later, President John F. Kennedy, concerned over inflation, jawboned the steel companies after they hiked prices, saying, "My father always told me that all businessmen were sons of bitches." One steel magnate retorted that "higher steel prices cause inflation like wet streets cause rain." Ultimately the industry retracted some of its price increases.

Weighing Social Factors

So while there are disagreements, "Usually it's over business issues," said Richard Sylla, a professor of economics at the New York University Stern School of Business. But here, "the business leaders are taking a moral stance on fundamental American issues."

President Donald Trump listens as Intel CEO Brian Krzanich speaks in the Oval Office of the White House in Washington on Feb. 8, 2017. Pablo Martinez Monsivais / AP file

Business leaders have to weigh these upsides against the prospect of employee and customer backlash against being associated with a polarizing president. On Tuesday afternoon, #QuitTheCouncil started trending on Twitter as customers began using it to pressure companies into leaving the advisory groups.

No longer buying @CampbellSoupCo until their CEO decides to #quitthecouncil. And my apartment buys a lot of soup. — Gordon Murphy (@gordonmurphy88) August 15, 2017

Trump’s main advisory council was created in December last year, before he took office, and met for the first time in February with the goal of offering help to further job creation. Council chair Stephen Schwarzman of Blackstone said at the time that one of the group’s purposes was to “de-bottleneck some things.”

That initial White House meeting was led by President Trump and included JPMorgan’s Jamie Dimon, Walt Disney’s Bob Iger, Wal-Mart CEO Doug McMillon, Pepsi CEO Indra Nooyi, and Mary Barra of General Motors. Vice President Mike Pence and White House Chief Strategist Steve Bannon, Trump’s daughter Ivanka, and son-in-law Jared Kushner also attended.

Following that session, Jack Welch, former CEO of General Electric, gushed about the president’s engagement and even termed it “a fabulous meeting.” The executives around the table were reportedly dispatched with homework and asked to report at a later date.

Since then, though, Kamarck said the companies may have contributed to discussions on getting rid of regulation, but besides the February meeting the group had accomplished "nothing substantive."

Levick had a bit of PR advice for the president: "It's time to disband the councils."

CORRECTION (3:10 p.m., Aug. 15): A previous version of this article misidentified the president who first said businesses were "malefactors of great wealth." The phrase was first used by Theodore Roosevelt in 1907, not Franklin D. Roosevelt in 1930s. (FDR used the line when quoting his fifth cousin Theodore.) The article also misidentified the Roosevelt who was the target of J.P. Morgan’s ire. It was Theodore, not Franklin.