“We are planning on playing here,’’ Eric Grubman said as dozens of people worked nearby to clear snow and ice from the outdoor facility. “If we can’t, at that point we’ll figure out what we’ll do next.’’

Despite an offer from the Indianapolis Colts to host the matchup at Lucas Oil Stadium, and concern from some Bears and Vikings players, Grubman called football a “cold-weather sport’’ and noted that several other NFL teams, including Buffalo and Kansas City, play in outdoor stadiums with no heating systems to keep their fields warm.

Grubman toured the University of Minnesota stadium and described it as “terrific.’’ He also looked at the snow-damaged Metrodome, where repair work was temporarily halted because of unsafe conditions four days after the roof collapsed under the weight of snow and ice — an accident that forced the Vikings to play Monday’s game in Detroit and a lot of scrambling to figure out the logistics for the game against Chicago.

Grubman declined to talk about backup plans or deadlines for a final decision because, he said, they wouldn’t come into play unless TCF Bank is deemed unsuitable.

The current plan isn’t exactly going over well in Chicago.

Bears safety Chris Harris said he understood why the Vikings want to play their home finale in Minnesota “but, at the end of the day, you’ve got to be safe.’’

“The NFL is cracking down on all this player safety and fining people $75,000, $50,000 for a hit because they want the game to be safer,’’ Harris said. “I don’t think it’s very safe to play on a frozen field.’’

Bears quarterback Jay Cutler, who suffered a concussion in a game this season, said the condition of the field was “the main concern with the guys in the locker room.’’

University officials said they planned to use a tarp over heating coils to soften the field before the game.

TCF Bank Stadium seats 50,000 fans, which means about 14,000 ticket-holders could be out of luck.

Vikings shuffle QBs The Vikings placed quarterback Tarvaris Jackson (turf toe) on injured reserve, ending his season. With Brett Favre still ailing and held out of practice, that means rookie Joe Webb is likely to get the start against Chicago. Webb has seen limited snaps in two games this season.

Minnesota signed veteran quarterback Patrick Ramsey to serve as a backup. Ramsey was let go by Miami last month.

Favre said he still feels discomfort in his sprained shoulder and numbness in his hand 11 days after getting hurt. He said “there’s no way’’ he would consider playing against the Bears with the same symptoms.

As for whether he’d like to play once more before he retires, Favre said he considers the entire season — his 20th in the NFL — the last hurrah.

“I knew going in, as with any season, there are no guarantees, and things may not go as you would have hoped,’’ Favre said, adding: “If it’s meant to be over, then so be it.’’

Cassel’s role unclear Chiefs quarterback Matt Cassel was limited in practice and his availability for Sunday’s game at St. Louis remained unclear. Cassel underwent an emergency appendectomy Dec. 8 and missed last weekend’s game at San Diego . . . Tim Tebow is getting more snaps at practice with starter Kyle Orton nursing bruised ribs and the rookie might even get his first extended action of the season when the Broncos visit Oakland Sunday . . . Browns coach Eric Mangini named rookie Colt McCoy his starting quarterback for the remainder of the season.

Revis feeling sore Jets cornerback Darrelle Revis has been limited at practice by “a little soreness’’ in his right hamstring, but expects to play Sunday at Pittsburgh. Coach Rex Ryan said he will start cornerback Dwight Lowery at safety with Eric Smith out with a concussion . . . Steelers tight end Heath Miller missed practice because of an exercise-related headache, putting his status for Sunday in question.

Whitner may split Unhappy with the Bills’ latest contract offer, safety Donte Whitner is eyeing the possibility of becoming a free agent. Whitner said he and the Bills are far apart in negotiations after talks this week. “It’s not looking good right now,’’ Whitner said . . . Two people with direct knowledge of the decision told the Associated Press Cowboys linebacker Anthony Spencer was fined $12,500 by the NFL for knocking helmets with Philadelphia quarterback Michael Vick Sunday night . . . The NFL sent a letter to every team reminding them of the rules and restrictions for the bench area and sidelines. The letter was sent in the wake of Jets strength and conditioning coach Sal Alosi being suspended indefinitely and fined $25,000 by the team for sticking out his knee and tripping Miami’s Nolan Carroll in Sunday’s game.