Allen, who reportedly took the snaps with the first-team offense Thursday, will be under center against Louisiana-Monroe on Saturday as the Aggies try to end a three-game losing streak.
Hill had a dynamite start to the season, leading the Aggies to a 5-0 record. He threw for a school-record 511 yards and three touchdowns in Texas A&M's 52-28 romp of South Carolina on Aug. 28 and averaged 349 passing yards per game while throwing for 17 touchdowns and two interceptions in his first five starts.
He was adorned with a nickname ("Kenny Trill"), was mentioned as a potential Heisman Trophy candidate and appeared on track for an impressive year.
Since, however, the Aggies have dropped three straight, prompting the coaching staff to re-evaluate the quarterback position.
In the past three games, Hill has averaged 301.3 yards per game and has thrown for six touchdowns along with six interceptions. The Aggies' offensive line struggled to protect Hill in those games, however, allowing 11 sacks after allowing only four in the first five.
Allen, who enrolled at Texas A&M in January and was the No. 1-ranked pocket passer in the 2014 recruiting class, has seen action in four games this season as a backup, completing 23 of 38 passes for 264 yards and three touchdowns with two interceptions.
Information from ESPN.com's Sam Khan Jr. is included in this report.