Sources said the Heisman Trophy winner was scheduled to visit the Raiders next week and would likely sign on as a backup to fellow USC alum Carson Palmer.
ESPN said Leinart would be penciled into the No. 2 slot ahead of Terrell Pryor.
Leinart last played with the Houston Texans after seeing only modest success with the Arizona Cardinals.
Notable deaths of 2014 [PHOTOS]
UPI Sports Results for September 19, 2014