The short version: a prominent Republican has rebuked the president, meaning she publicly called out her own party's leader over his immigration policies and said Hispanic voters feel betrayed. That Republican is María Elvira Salazar, a Florida lawmaker. She made the charge in a television advertisement, describing the policies as heavy-handed.
Salazar's standing gives the ad weight. She is a member of the same party as the president, which makes her rebuke something different from standard political opposition. A lawmaker who shares a party with the president and runs a television advertisement against him has moved the argument out of private conversation and into public view.
The word choice is the most pointed part. She landed on "betrayed," not a softer word. Betrayal implies a promise was made to Hispanic voters and then broken. Salazar framed the problem as a breach of faith, not a difference of opinion over tactics.
Running a television advertisement means she decided the message needed a broad audience. The criticism is now on record in a format the public and press can reference. Her focus is the approach to immigration enforcement, which she called heavy-handed, a term that suggests blunt policies applied without much flexibility.
Salazar is the Florida lawmaker described as a top Republican, and the one who carried that charge to television.