IRVING, Texas - The Dallas Cowboys are bringing back Jon Kitna to be their third-string quarterback, according to a source.

Kitna played 15 seasons in the NFL, his last three with the Cowboys before he retired after the 2011 season. He returned to his high school alma mater - Lincoln High in Tacoma, Wash. - to be a football coach and math teacher.

As Tony Romo's backup, Kitna, 41, was a locker-room leader for the Cowboys.

On Tuesday at Valley Ranch, the Cowboys worked out quarterbacks David Carr, John Skelton, Tyler Thigpen, and Caleb Hanie, who was born in Dallas.

Kitna would be the Cowboys' backup quarterback Sunday if Kyle Orton starts in place of Romo. Kitna also will help the Cowboys get through practices this week with Romo out.

The Cowboys aren't taking Christmas off. They will practice at 2:30 p.m. at Valley Ranch.

Kick returner Micheal Spurlock was released to make room for Kitna. Spurlock returned a punt 62 yards in Sunday's win at Washington that set up the Cowboys' first touchdown.

Lee still out

The Cowboys also could be without their quarterback on defense for a third consecutive game.

Middle linebacker Sean Lee hasn't been cleared by doctors to begin practicing as he recovers from a sprained ligament in his neck.

"If we could get him on the field, that would be a real positive," Cowboys owner Jerry Jones said Tuesday.