The head of Hispanic media relations at the Republican National Committee is resigning this month in what appears to be another indication of the lingering discomfort some party officials have about working to elect Donald J. Trump president.

Ruth Guerra, who is of Mexican descent and was in charge of carrying the party’s message to Hispanic voters, is joining the American Action Network, a Republican-aligned “super PAC,” she confirmed in a brief interview on Wednesday.

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But Ms. Guerra told colleagues this year that she was uncomfortable working for Mr. Trump, according two R.N.C. aides who requested anonymity to speak candidly about the difficulties surrounding the party’s presumptive standard-bearer.

It is relatively rare for party staff members to leave the national committee in the midst of a presidential campaign unless they are going to work directly for the nominee.