JACKSONVILLE, Fla. -- Blake Bortles is done as the Jaguars' starting quarterback -- for 2018, anyway.

Coach Doug Marrone said backup Cody Kessler will take over for the rest of the season, beginning with Sunday's game against the Indianapolis Colts at TIAA Bank Field, as the Jaguars (3-8) try to snap a seven-game losing streak. He announced the move on Monday several hours after firing offensive coordinator Nathaniel Hackett.

"It's not a knee-jerk reaction," Marrone said. "I really feel like at the end of the day we've got to try to get better production out of our passing game or more consistent production in our passing game."

Bortles, who is 24-48 as a starter, has played poorly this season despite completing a career-high 60.4 percent of his passes. He has thrown for less than 150 yards in four of his past six games, was benched against Houston on Oct. 21 after losing two fumbles, and has thrown just 13 touchdown passes and 10 interceptions. Per ESPN Stats & Information, Bortles' Total QBR of 49.0 ranks 25th among 31 qualified quarterbacks this season. He ranked 12th last season, when he threw 21 touchdown passes and 13 interceptions and helped lead the Jaguars to the AFC Championship Game.

Bortles did throw for 376 yards and a career-high four touchdowns in the Jaguars' victory over New England in Week 2, 388 yards in a Week 4 victory over the New York Jets and a career-high 430 yards in a Week 5 loss at Kansas City. He also threw a career-high four interceptions and lost a fumble in the Chiefs game.

Turnovers have been Bortles' biggest issue. He leads the NFL in turnovers (93) and interceptions (74) since he entered the league in 2014. Yet he also is second in franchise history in passing yards (17,500) and passing touchdowns (103) in 72 starts.

In what could be the last start of his Jaguars career, Bortles completed 12 of 23 passes for 127 yards and one touchdown with two interceptions in Sunday's 24-21 loss at Buffalo. One of his interceptions was a pass thrown behind receiver Keelan Cole that got tipped. The other was a good throw that bounced off tight end James O'Shaughnessy's hands.

Bortles also badly underthrew Cole on another short pass in which the ball fluttered after it left his hand and was off the mark by several yards.

Bortles might not start again this season, but he still might have a future with the Jaguars. He signed a three-year, $54 million contract extension in February that lasts through the 2020 season. He is due a $1 million roster bonus on the fifth day of the 2019 league year and has $6.5 million of his 2019 base salary guaranteed.

If the Jaguars want to cut him after this season, it would cost them $16.5 million in dead money, though that figure drops to $9.5 million after June 1.

Kessler, whom the team acquired in a trade with the Cleveland Browns for a seventh-round pick in March, is 0-8 as a starter and has a 45.1 Total QBR (per ESPN Stats & Info). All of those starts came in his rookie season in 2016 with the Browns, who drafted Kessler in the third round out of USC.

Kessler has thrown for 1,662 yards and seven touchdowns with four interceptions. He completed 21 of 30 passes for 156 yards and one touchdown with one interception after replacing Bortles against the Texans earlier this season.

Kessler will have a new playcaller in Scott Milanovich, who was hired as the team's quarterbacks coach last season after Hackett was promoted to offensive coordinator. Milanovich, who led the CFL's Toronto Argonauts to a 43-47 record and one Grey Cup title in four seasons as their head coach (2012-16), has previously served as an offensive coordinator with four teams, including the Rhein Fire (2005) and Cologne Centurions (2006) of NFL Europe and the CFL's Montreal Alouettes (2008-11).

The Jaguars' offense under Hackett in 2017 was one of the NFL's most productive, leading the league in rushing and finishing sixth in total offense and fifth in scoring. However, the offense has regressed in 2018, partly because of a large number of injuries (seven starters or key reserves have missed multiple games, including running back Leonard Fournette) but also because of Bortles' poor play.

The Jaguars rank 22nd in total offense, 16th in rushing, 22nd in passing and 28th in scoring. The Jaguars either had the lead or had a chance to take the lead in the fourth quarter of each of their past four games yet failed to win.

"I felt I needed to make a change to get us an opportunity to win some games," Marrone said of his decision to fire Hackett, who had coached with Marrone the past nine seasons at Syracuse, Buffalo and Jacksonville.

In addition, Kessler could be without the Jaguars' best offensive player. Fournette was ejected from Sunday's game after getting into a fight with Bills defensive end Shaq Lawson and is expected to be disciplined by the league. That could include a suspension.

The Jaguars also lost another starting offensive lineman Monday when Marrone said the team would be placing left guard Andrew Norwell on injured reserve because of an ankle injury he suffered against the Bills. Norwell, whom the team signed to a five-year, $66.5 million contract with $30 million guaranteed in March, is the fourth Jaguars starting offensive lineman to end up on IR.

Left tackle Cam Robinson (knee), his replacement Josh Wells (groin) and center Brandon Linder (knee) also are on IR, although the team is hoping to bring Wells back later this season.