LAS VEGAS >> Can’t decide the winner in your March Madness bracket? Don’t feel bad. Las Vegas casinos can’t agree on an NCAA Tournament favorite, either.

The Wynn Las Vegas and Westgate SuperBook originally listed Duke as the odds-on pick to win college basketball’s national championship on Sunday. But both books switched to North Carolina as the favorite on Tuesday, less than 48 hours after the brackets for the tournament were revealed.

Meanwhile, MGM Resorts International had Kansas as a 5-1 favorite, while William Hill opened with North Carolina and tightened its odds after early wagers.

“This year, a lot of people believe there are eight to 12 teams that can take home the tittle,” said Jay Kornegay, Westgate’s sports book director. “The odds are so close in the top contending teams that any time you have an influx of money, that can change the odds and make that team the favorite at that time.”

At Westgate, North Carolina was followed by Kansas at 6-1 — which leapfrogged original favorite Duke. The Blue Devils were at 7-1 and top overall seed Villanova at 8-1.

“It’s uncommon; it’s a wide-open year,” said Nick Bogdanovich, head oddsmaker for William Hill, which runs more than 100 sports books in Nevada. “Usually, there are seven or eight teams that you can narrow it down to. But this year, I think there are more teams that can win it than ever before.”

The American Gaming Association, a lobbying group for commercial and tribal casinos, estimates that about $10.4 billion will be wagered on the three-week hoops extravaganza that starts Tuesday night with play-in games and ends April 3 with the national championship game in Phoenix. That’s $1.2 billion more than last year and only $295 million of that will be bet legally, mostly at sports books in Nevada.

Las Vegas casinos are getting ready for large crowds, so much so that some resorts open overflow areas to accommodate basketball fans. To get a seat, some will start lining up early Thursday.

Johnny Avello, the longtime oddsmaker and sports book director for the Wynn Las Vegas, said Duke was his favorite despite the ups and downs the team saw this year.

“They could have been worthy of a 1-seed, but the committee gave them a 2-seed… They deserved to be my top team going into the tournament,” Avello said. “Plus, we’ve taken money on them all year.”

Sports books are also taking proposition bets — unique wagers offered on specific outcomes — including on how many tournament games the Big East Conference will win and the number of total No. 1 seeds that will reach the Final Four.

Neither Villanova nor Gonzaga, two No. 1s, were top favorites on Tuesday. Oddsmakers said that while Gonzaga got a top seed, it doesn’t face strong competition throughout the year, while Villanova has to overcome being the defending champion.

“That puts a target on their backs a bit,” Kornegay said.

At MGM, Kansas has double the popularity of Villanova based on the number of bets booked. There, the Jayhawks have remained the favorites since before the seeding announcement.

“If this was an election, Kansas would win by a landslide,” said Jay Rood, MGM’s vice president of race and sports books.