Team and league sources said that former starter Byron Leftwich will likely be traded or released.
Leftwich missed 15 games the last two seasons because of an injured left ankle. He had surgery last November, more than a month after coach Jack Del Rio benched him in favor of Garrard.
The Jaguars have been actively calling teams around the league to gauge interest in Leftwich, who is in the last year of his contract. He had been designated as the starter in the offseason by Del Rio.
Team sources said Garrard's continued development in training camp and preseason convinced Del Rio that Garrard was the right quarterback for the team.
The Jaguars are also trying to acquire a veteran quarterback to serve as a backup and may turn to former Jaguars quarterback Mark Brunell.
Garrard went 145-of-241 for 1,735 yards, 10 touchdowns and nine interceptions last season, with a passer rating of 80.5.
Leftwich was 108-of-183 for 1,159 yards, seven TDs and five interceptions last season, with a passer rating of 79.0.