The Minnesota Senate took up the Vikings stadium bill on Tuesday after a lengthy behind-closed-doors debate on the subject by GOP senators.

The Senate began debating the issue around 1 p.m., four hours after the session was originally to convene. Senate Majority Leader Dave Senjem, R-Rochester, called for private caucuses to debate the bill. After the meeting, Senjem said he believes the Senate vote will be close -- probably a one-vote margin.

The outcome is uncertain in the Senate, where 34 votes are needed for passage. Even if it does win today, it will likely have to be reconciled with a separate House version in a House-Senate conference committee later this week.

If that happens, the compromise version would have to return to each House for a final vote before going to Gov. Mark Dayton for his signature.

The House voted 73-58 Monday night to pass an amended version of the bill. The House bill calls for another $105 million contribution from the team to stadium construction, which a team spokesman has called "not workable." The House would increase the team's total contribution to the construction to $532 million, with the state paying $293 million and the city of Minneapolis $150 million.

The House bill also made the team responsible for cost overruns and shared revenue from stadium "naming rights," in which corporations pay to have their name affixed to the building.

Harry Melander, president of the state's Building and Construction Trades Council, and David Olson, President of the Minnesota Chamber of Commerce, sent a joint letter of support in advance of the Senate vote. "We recognize that this is a tough vote, particularly in an election year," the statement read. It called on "a balanced approach from both sides of the political aisle" to pass the bill.