Donald J. Trump says he is starting to win over skeptical Hispanic voters, but his opponents are investing in a new advertising campaign in Arizona, Florida and North Carolina to make sure that does not happen.

A blitz of radio ads funded by the progressive advocacy group People for the American Way is set to air in the three states Thursday morning and to run throughout the week. The bilingual ads will feature fearful children asking their parents about Mr. Trump, and they will target Republican lawmakers who are supporting the Republican presidential nominee.

“I’m scared of Donald Trump, Mom,” a child says in English in one of the ads. “Are you going to vote against him?”

The conversation then switches to Spanish, with the child expressing concern about Mr. Trump’s big rallies and the mother responding, “We can’t allow him to win.”