WASHINGTON ― A CEO serving on President Donald Trump’s council on manufacturing announced his resignation early Monday from the White House panel, in protest of Trump’s initial silence on the white nationalist groups who incited Saturday’s deadly violence in Charlottesville, Virginia.

Ken Frazier, the head of Merck pharmaceuticals, said in a statement he was stepping down “as a matter of personal conscience” and “to take a stand against intolerance and extremism.”

By Monday night, several CEOs joined Frazier in resigning from the council, over Trump’s response to Saturday’s violence. But other CEOs affirmed that they would remain on the council, their representatives told HuffPost.

Kevin Lamarque / Reuters President Donald and Merck & Co. CEO Ken Frazier at a White House meeting in February.

In response to Frazier’s departure, Trump ― who did not personally denounce the far-right groups that sparked Saturday’s deadly carnage in Charlottesville until Monday afternoon ― directly attacked Frazier on Twitter.

Now that Ken Frazier of Merck Pharma has resigned from President's Manufacturing Council,he will have more time to LOWER RIPOFF DRUG PRICES! — Donald J. Trump (@realDonaldTrump) August 14, 2017

His tweet was one of several posted on Monday morning, ranging from attacking “obstructionist Democrats” to pledging he would work on “trade and military” and reiterating his support for Sen. Luther Strange (R-Ala.), who is squaring off against several opponents in a GOP primary on Tuesday.

None of his tweets addressed the weekend’s violence.

After Trump on Saturday had blamed “many sides” for the hatred that led to the violence in Charlottesville, the White House on Sunday said in a statement that “of course” that included “white supremacists, KKK Neo-Nazi and all extremist groups.”

Still, the statement was attributed to an unnamed spokesperson, not to Trump himself.

This article has been updated to note other CEOs also resigned and that Trump finally denounced the far-right groups Monday afternoon.