The Dallas Cowboys have placed their exclusive franchise tag on Dak Prescott, securing the rights to their star quarterback for an estimated $31.5 million while the sides continue working on a long-term deal.

The Cowboys announced the decision on their website about an hour before the deadline for teams to designate the franchise tag.

By using the tag on Prescott, the Cowboys will keep working to get a deal with Amari Cooper as the receiver gets set to become an unrestricted free agent when the new league year starts, currently planned for Wednesday.

The Cowboys and Prescott have been working on a deal for about a year. The two-time Pro Bowler was one of the best bargains in the NFL last season with a base salary of $2 million as a fourth-round pick in 2016.

Prescott was the 2016 NFL Offensive Rookie of the Year when he led the Cowboys on a franchise-record 11-game winning streak that vaulted them to the top seed in the NFC before losing to Green Bay in the divisional round.

Dallas made the playoffs again in 2018, with Prescott getting his first wild-card win, before falling short of high expectations by missing the postseason last year. The Cowboys didn’t renew coach Jason Garrett’s contract after the disappointing season and hired Mike McCarthy.

With the NFL’s offseason likely to be altered by the coronavirus pandemic, the Cowboys could have more opportunity to get a long-term deal with Prescott before he misses valuable time working with a mostly new coaching staff.

Prescott has the option of signing the franchise tender and guaranteeing his huge pay increase, but is likely not to sign it to help his leverage in negotiations.

When he was drafted, Prescott was the third-team quarterback behind Tony Romo and Kellen Moore. But preseason injuries to both made Prescott the starter, and Romo never got his job back.

Cowboys owner Jerry Jones has said repeatedly he considers Prescott his franchise quarterback, and it’s just a matter of time before a deal gets completed.

Dallas traded a first-round pick to Oakland for Cooper during the 2018 season. Cooper finished that year strong and was solid in the first half of 2019 before tailing off as the season progressed.