Dallas Cowboys quarterback Tony Romo will miss the rest of the season because of a back injury, a league source told ESPN NFL Insider Adam Schefter on Monday.

Romo has a herniated disk in the lumbar region and needs to have surgery, a source told ESPN Senior NFL Insider Chris Mortensen.

At his weekly news conference, coach Jason Garrett wouldn't rule Romo out, instead saying he would receive treatment each day this week and the team would evaluate the quarterback's injury each day.

"We just have to take it day by day," Garrett said.

The Cowboys (8-7) host the Philadelphia Eagles (9-6) on Sunday night, with the winner capturing the NFC East title. Kyle Orton likely will get the start at quarterback for Dallas.

Orton has 69 career starts and is 35-34. He hasn't started since the 2011 regular-season finale with Kansas City.

Garrett said the Cowboys likely will sign another quarterback this week, as Orton is the only backup on the roster.

"We have Kyle Orton here for a reason," Garrett said, adding that Orton prepares as though he's the starting quarterback each week.

Romo said Sunday he would undergo an MRI on his back Monday but didn't believe the injury would jeopardize his availability for the Philadelphia game.

Romo said his back, which was sore going into Sunday's comeback victory over the Washington Redskins, began to bother him after a hit in the first half.