Simon & Schuster Chief Executive

Jonathan Karp

sent an internal letter last week rejecting the employee demands, when the company was aware the petition was circulating.

It has now been formally submitted. A spokesman for Simon & Schuster on Monday declined to comment.

The 216 employees who signed the petition represent about 14% of Simon & Schuster’s workforce. Among the more than 3,500 outside supporters, according to a letter accompanying the petition, were writers of color including

Jesmyn Ward,

a two-time winner of the National Book Award for fiction. A representative for Ms. Ward confirmed that she signed the petition.

The petition and letter were sent to Mr. Karp and

Dana Canedy,

publisher of Simon & Schuster’s flagship imprint.

The petition accused Mr. Pence of advocating for policies that were racist, sexist and discriminatory toward LGBT people, among other criticisms of his tenure as a public official. The petition also calls on Simon & Schuster to cut off a distribution relationship with Post Hill Press, a publisher of conservative books as well as business and pop culture titles.

A spokesman for Mr. Pence declined to comment. Post Hill Press publisher

Anthony Ziccardi

said, “We’re proud of our publishing program, that’s what we’re focused on.”

In rejecting the group’s demands, Mr. Karp last week said in his internal letter that Simon & Schuster’s core mission includes publishing “a diversity of voices and perspectives.”

The letter from Simon & Schuster employees on Monday said, “When S&S chose to sign Mike Pence, we broke the public’s trust in our editorial process, and blatantly contradicted previous public claims in support of Black and other lives made vulnerable by structural oppression.”

Bertelsmann SE has agreed to acquire Simon & Schuster from

ViacomCBS Inc.

for almost $2.18 billion. The deal is expected to close later this year, pending regulatory approval.

Write to Jeffrey A. Trachtenberg at jeffrey.trachtenberg@wsj.com