Carly Fiorina deserves to be in the next prime time debate, she said Friday.

“Based on every meaningful metric, I’ve earned a place on the main stage,” Mrs. Fiorina wrote in an email to The Wall Street Journal.

Mrs. Fiorina’s claim to a spot in the big show is the latest salvo in her campaign’s effort to pressure CNN, which is airing the Sept. 16 debate from the Reagan Library in Simi Valley, Calif., to alter its rules to allow her better odds of appearing with the first-tier candidates.