LAS VEGAS >> It looked like a mismatch even before Peyton Manning hooked up for his first touchdown pass to Wes Welker and the rest of the NFL found out just how bad the Jacksonville Jaguars really are.

But now it’s official. The Denver Broncos are the biggest favorite ever in an NFL game in this gambling city, a whopping four-touchdown pick Sunday at home against the hapless Jaguars.

Sports books in and around Las Vegas make Manning and the Broncos a 28-point favorite over Jacksonville, unheard of in an industry where half-point swings can be huge and most teams are rated within a few points of each other. But even the big line hasn’t stopped people from betting money on the Broncos, even after they didn’t cover the spread in Sunday’s 51-48 win over the Dallas Cowboys.

“It didn’t take people long to jump on the Broncos bandwagon, which is at its capacity now,” said Jay Kornegay, who runs the sports book at the LVH hotel. “And we expect that to continue.”

Though the city’s legal sports books don’t keep historical records on such things — and the NFL refuses to even acknowledge that betting lines exist — those in the industry say the lopsided point spread surpasses the 26-point margin for favored Pittsburgh against Tampa Bay in 1976 when the Buccaneers were an expansion franchise and the Steelers got within a game of the Super Bowl.

More recently, the biggest favorite was New England as a 24-point pick over Philadelphia in 2007, the year the Patriots made it through the regular season undefeated.

“You have a team that can’t seem to get out of their own way against a team that put up 51 points on Sunday,” said Jimmy Vaccaro, vice president of sports marketing at the South Point hotel. “Everything feeds into this. It’s the best versus the worst.”

The game is so lopsided that most sports books aren’t even putting up money lines on the game, where a bettor can simply pick a team to win or lose. Instead, oddsmakers tried to find a number that would somehow entice betting on the Jaguars even if they are given almost no chance of winning the game outright.

That line turned out to be 28 points, meaning bettors who think Manning and the Broncos won’t let off the gas at home against Jacksonville have to give up that many points to get a bet on Denver. Those who like Jacksonville, on the other hand, will start with a four-touchdown edge on their bets.

“You might want to get out the Farmer’s Almanac and hope they have 14 feet of snow Saturday night in Denver if you’re taking the 28,” Vaccaro said. “But it’s still the NFL, where anything can happen.”

Denver bettors found that out Sunday when the Broncos — who were heavily bet as 7 1/2 -point favorites in Dallas — failed to cover the spread for the first time this season. Before that, bettors were cashing in tickets by the handful on the Broncos and on the total score going over what oddsmakers thought it would be.

“Dallas was America’s Team but it’s definitely Denver now,” Vaccaro said. “It’s all because of Manning, too. He’s revitalized the whole franchise and made them the Super Bowl favorite.”

Kornegay said the city’s sports books have had a good year so far taking money on the NFL, though the tremendous popularity of the Broncos has cost them some money. He said it was reminiscent of the 2007 season, when bettors kept putting money on the Patriots until oddsmakers got wise and raised the lines so much it was tough for even a dominant team to cover the spread.

RJ Bell, who runs a website that analyzes betting and betting patterns, said casual bettors will continue to back the Broncos no matter what, while the professionals are more about where the numbers actually end up.

“If you say this line is 28 or even 32 points the average bettor just shrugs and figures Peyton Manning will score no matter what,” he said.

For those who do like the Jaguars, there is recent historical precedence for betting them. In the 2007 game where New England was favored by 24 over Philadelphia, the Patriots didn’t come close to covering the spread in a 31-28 win.