WASHINGTON — The National Association of Manufacturers, a powerhouse business lobbying group, welcomed President Trump to its annual meeting in September 2017. Its president, Jay Timmons, introduced Mr. Trump as “a true champion for our industry, who has fought for manufacturing since Day 1 of his presidency.”

This past week, as insurgents seeking to overturn Mr. Trump’s re-election defeat stormed the U.S. Capitol, Mr. Timmons and his association issued a severe statement calling for the president’s removal from office via the 25th Amendment of the Constitution.

“This is chaos,” the statement read. “It is mob rule. It is dangerous. This is sedition and should be treated as such. The outgoing president incited violence in an attempt to retain power.”

The statement was the culmination of months of mounting frustration in the organization over shortcomings in the Trump administration’s response to the Covid-19 pandemic and, more recently, Mr. Trump’s contesting of the election result. It was also the product of rising anger from Mr. Timmons, who has blamed Mr. Trump and other political leaders for his father’s death from the virus last month.

The public rebuke was an extraordinary break between Mr. Trump and a major business lobbying group that worked closely with him to secure tax cuts and regulatory rollbacks during his term and that the president has showered with attention and praise.

Mr. Timmons and his leadership team did not poll association members before calling for Mr. Trump’s removal, though the executive committee agreed to the group’s increasingly emphatic news releases after the November election calling for an orderly transfer of power to President-elect Joseph R. Biden Jr.

“The Capitol of the United States was being stormed at the instigation of the president of the United States and his lawyer,” Mr. Timmons said in an interview Friday. “It was a clear and present threat to our democracy. I thought it was really important to speak up.”

Mr. Timmons declined to say whom among his association’s leadership team he had consulted before issuing the statement. He said that most members supported the statement and that he had received messages of thanks from some Trump administration staff members, whom he did not name.

Still, the statement — which took aim at a president who has spent the past four years championing American manufacturing — stirred opposition from some corners of the association.

Steve Staub, president of Staub Manufacturing Solutions, which focuses on metal fabrication in Dayton, Ohio, said in email that he did not support the statement. He declined to say what he objected to or whether he might resign from the executive committee of the association’s board.

Mr. Staub has supported Mr. Trump enthusiastically in the past. He attended the 2018 State of the Union address as a guest of the White House. He and his wife attended a White House holiday party in December 2018, leading him to say, “We’re humbled to be included in an event like this and glad that our president cares about the manufacturing industry and small businesses like ours.”

Other members of the executive committee said they backed the statement. They included Karl Hutter, chief executive of Click Bond, an aerospace manufacturer, and Rice Powell, chief executive of Fresenius Medical Care, a company that provides products and services for people with chronic kidney failure.

In a statement to Fresenius employees, Mr. Powell said: “Disagreement among citizens regarding matters of politics and policy is commonplace — even healthy — to our republic. Violence and insurrection are not.”

Mr. Trump made a revival of manufacturing a key plank of his 2016 campaign and a focus of his presidency. He imposed tariffs on foreign steel and aluminum to help American manufacturers like U.S. Steel and Century Aluminum and on $360 billion worth of Chinese goods as punishment for China’s siphoning of factory jobs away from the United States.

The manufacturers’ association does not donate money to presidential candidates, but it quickly found favor with the new administration.

Mr. Timmons urged his members to promote Mr. Trump’s 2017 tax cut proposals on social media, leading to praise from Mr. Trump for his hard work on the issue. The group also pushed the administration to roll back a wide range of regulations and celebrated an executive order Mr. Trump signed in 2019 allowing firms to speed up their construction of gas and oil pipelines. More than 400,000 manufacturing jobs were added during Mr. Trump’s first two years in office, and the organization’s influence and membership grew.

Manufacturers split with Mr. Trump on immigration policy and, most notably, trade, opposing tariffs that Mr. Trump began to impose in 2018. But this year the rift widened considerably.

In the spring, Mr. Trump named Mr. Timmons to an industry group advising the administration on reopening the economy safely in the pandemic. But in April, Mr. Timmons vented on Facebook and in an interview about protesters who were pushing for a fast reopening when many manufacturers were struggling to secure personal protective equipment for their workers.

Mr. Trump was encouraging the protests and demanding the lifting of government restrictions on activity, but at the time, Mr. Timmons declined to criticize him publicly. “I’m not going to get into that,” he said. “I’m going to use my platform to say what I believe is right and what I believe is good for my manufacturing workers.”

The association congratulated Mr. Biden after the election was called in his favor. Nearly two weeks later, it released a statement urging federal officials to ascertain Mr. Biden as president-elect and start the formal transition of power. On Jan. 4, the group denounced efforts by Mr. Trump and congressional Republicans to challenge certification of Mr. Biden’s victory. Each of those releases followed extensive conversations among members of the executive board.

The release on Wednesday did not involve the same level of debate. Mr. Timmons said the attacks at the Capitol violated the association’s core values. As rioters stormed the Capitol, the association staff convened a Zoom call, assembled the statement and released it by midafternoon.

“Vice President Pence, who was evacuated from the Capitol, should seriously consider working with the cabinet to invoke the 25th Amendment to preserve democracy,” it read. “This is not the vision of America that manufacturers believe in and work so hard to defend.”

Many members of the executive committee either did not comment or did not say whether they supported the association’s statement when asked. The committee includes representatives from some of the most prominent names in corporate America, such as Pfizer, Johnson & Johnson, Toyota, Dow Inc., Caterpillar, Goodyear Tire and Emerson Electric. Some of the companies released statements of their own about the invasion but would not say publicly whether they supported the trade group’s statement.

In a statement on Wednesday, Pfizer’s chief executive, Albert Bourla, called the events “deeply disturbing.”

Jim Fitterling, chief executive of Dow, released a statement during the unrest saying, “Scenes at the U.S. Capitol are an attack on democracy and not who we are as a country.”

Caterpillar’s chief executive, Jim Umpleby, also put out a statement condemning the violence.

Nick Pinchuk, chief executive of Snap-on, a tool maker, said in an email that he agreed with the association’s assertion that “this is not the vision of the America that we believe in and work so hard to defend.” But he said he was “dismayed to be confronted” with the question of whether the 25th Amendment should be used.

“Those with more studied perspectives of Washington are better equipped to guide that decision,” Mr. Pinchuk said.

Mr. Timmons acknowledged some dissent. “We’re a diverse organization. Not everyone’s going to agree with every word I say on behalf of the industry,” he said. But, he said, “we have had overwhelming — stunningly overwhelming — support from the membership on the statement.”

Jim Tankersley reported from Washington, and Peter Eavis and Lauren Hirsch from New York.