The head of publishing company Simon & Schuster refused a petition by employees to cancel a book by former vice president Mike Pence, in a letter to staff on Monday.

“As a publisher in this polarized era, we have experienced outrage from both sides of the political divide and from different constituencies and groups,” CEO Jonathan Karp wrote in the letter. “But we come to work each day to publish, not cancel, which is the most extreme decision a publisher can make, and one that runs counter to the very core of our mission to publish a diversity of voices and perspectives.”

“We will, therefore, proceed in our publishing agreement with Vice President Mike Pence,” Karp continued.