The Minnesota Vikings' lease at the Metrodome may require them to play one more season there, possibly erasing the team's claim of urgency in assembling a new stadium deal.

"We believe that the use agreement, because of the shortened season, calls for another year at the Dome," Metropolitan Sports Facilities Chairman Ted Mondale said Friday.

News of the clause came in a week that has seen dramatic ups and downs in the stadium's fortunes, with Gov. Mark Dayton first announcing an accord of sorts on possible funding options, then a collapse of talks when House Speaker Kurt Zellers said he opposed a special session, then a cautious restart on Thursday among stadium proponents.

The collapse of the Metrodome roof last winter in a freak blizzard forced the Vikings to play two of their 2010 season home games elsewhere. That, Mondale said, triggered the lease extension clause.

The Vikings disagree and say the agreement with the commission, which owns the Metrodome, expires by Feb. 1. If the National Football League team tries to leave, the dispute could land in court, a scenario similar to the commission's successful 2002 legal fight to keep the Minnesota Twins in the Metrodome.

Vikings Vice President Lester Bagley said the team's view is based on legal analysis of the lease. "It is not in the state's or anyone's best interest to look for any reason to further delay a stadium solution," he said.

Two key legislators who have participated in stadium discussions in Dayton's office said they knew of the clause, and Dayton said Friday he was unsure of the legal ramifications but did not think it should thwart the push to help the Vikings build a stadium.

"I don't think getting into that kind of legal wrangle with the Vikings is going to help," he said.

The commission's original lease agreement with the Vikings required the team to play at the Metrodome for 30 years, through the 2011 season. But what is known as a "force majeure clause" specifies that if the Metrodome is damaged and the team is forced to play elsewhere for even part of a season, the Vikings are obligated to play an additional full season at the Metrodome.

The clause states in part that: "For each football season, or part of football season, while this Agreement is suspended, the term of this Agreement ... shall be extended by one football season."

By legal definition, "force majeure" means an unavoidable circumstance or accident.

On Dec. 12, 2010, a blizzard collapsed the Metrodome's roof, forcing the NFL to move that day's Vikings-Giants game to Detroit's Ford Field. The Vikings played their final home game on Dec. 20 at TCF Bank Stadium against the Chicago Bears.

'It looked pretty clear'

A new roof was in place for the team's 2011 preseason games.

"As I read it, it looked pretty clear, but you could argue whether it was a full season or two games," Mondale said of the required makeup games. "I don't see a scenario where they aren't going to play at the Dome in 2012."

Although the commission successfully enforced the Twins' contract through Hennepin County District Court, Mondale said he believes an agreement will be reached out of court for the Vikings to stay in the Metrodome through the 2012 season.

The commission sent a written notice regarding the clause to the Vikings a month ago, but the team has not responded.

Senate Minority Leader Tom Bakk, DFL-Cook and a key stadium supporter, said he did not believe this development would affect the move to deal with the stadium proposal in a special legislative session.

Rep. Morrie Lanning, R-Moorhead, the chief House stadium bill author, downplayed the significance of the lease clause, but acknowledged that stadium opponents could point to the language as a reason to slow the push for a special session.

Lanning said the revelation about the clause doesn't mean "the pressure's off" to help the Vikings build a new facility.

"Whether technically the lease expires February 1 of 2012, or expires February 1 of 2013, is immaterial, in my view," said Lanning. Minnesota, he said, needs to address the Vikings' stadium needs and "get this off the front page."

The Vikings want a $1.1 billion stadium built in Ramsey County's Arden Hills. So far, there is no consensus among public officials on location, funding or even whether the team should get a public subsidy for a new stadium. Minneapolis has proposed three potential sites.

Under pressure from Bagley and the Vikings, Dayton had held out the prospect of a special session before Thanksgiving. That prospect flickered on and off each day last week, particularly after Zellers, the House speaker, said he opposed a special session.

On Friday, Mondale said the stadium won't be solved this month, adding, "I don't see this as a big urgency."

Minneapolis City Council President Barbara Johnson said the "force majeure clause" backs up what she has said before, that "there's no urgency here."

Give a year's notice

Delays could give Minneapolis time to advance their proposals, even though the Vikings say they are committed to Arden Hills.

Mondale said that if the Vikings wanted to leave Minnesota, they would be required to give a year's notice and have a deal in place with another city. The team has deliberately avoided any overt threats, but Bagley has said repeatedly that the team's situation gets more complicated if a stadium deal is not reached this season.

Mondale said the commission has a good relationship with the Vikings. He noted that years ago the commission cut the Vikings' rent in half, to $4 million, because of the team's financial situation.

"We're going to be accommodating to them," he said.

Staff writers Kevin Duchschere and Jim Ragsdale contributed to this report. Rochelle Olson • 651-925-5035 Twitter: @rochelleolson