Things were already strained at Simon & Schuster.

After backing out of a deal with Senator Josh Hawley, a prominent supporter of former President Donald J. Trump, the company announced this month that it would publish two books by former Vice President Mike Pence. Dana Canedy, who joined Simon & Schuster as publisher last year, called Mr. Pence’s memoir “the definitive book on one of the most consequential presidencies in American history.” That’s when much of the staff erupted in protest.