whoever (subject)
- The person or people who; any person who
- it does not matter who
whomever(object)
- when whatever person or people is/are the object of a sentence.
- I want to speak to whoever is in charge.
- I want to speak to whomever is in charge.
I think the second is correct because the subject wants to speak to the person, who is the object.
nobody
says 'whomever'.