Daniels suffered a season-ending knee injury in the opener last year, leading to Kedon Slovis' emergence as the Pac-12 Offensive Freshman of the Year.
Last month, USC seemed hopeful that Daniels would stay. But with Slovis penciled in as the starter, Daniels made the decision to explore his options. In a statement, Helton did not rule out Daniels' return to the team.
"We have been working with JT and his family, as well as our compliance office, to help him navigate the process of entering his name in the transfer portal," Helton said. "It is his desire to explore all of his options going into the 2020 season. We will continue to support JT in every way possible and help him through his decision, including the option of staying on with our football team."
Daniels, a four-star ESPN 300 prospect in the Class of 2018, has been rehabbing his knee but isn't expected to be fully ready for competition until at least the summer. Slovis threw for 3,502 yards, 30 touchdowns and nine interceptions last year.