A key Council supporter of the mayor's Vikings stadium plan said he would "potentially" change his vote if an independent panel clashes with the city attorney's stance on a citywide vote.

The city attorney and the mayor say the plan doesn't trigger a charter requirement to hold a vote since the relevant taxes are not controlled by the city. But Council Member Kevin Reich broke with stadium supporters Tuesday night when he approved a measure asking the city's charter commission to conduct its own analysis.

A 'no' vote from Reich would eliminate Rybak's slim seven-member majority support on the 13-member Council, something state lawmakers say is crucial for the bill's passage. Reich was one of two swing votes who waited weeks to pledge their support.

“I think it’s a fair exploration," Reich said of the charter commission review. "I think we should always be exploring every important issue and every big decision. We should do as much research and due diligence as possible."

He added that he is “open to their findings,” but the charter commission does not have a “trump card.”

"They’re a thoughtful body. They’re a germane body. But then again, they play their role and our city attorney plays her role.”

Charter Commission Chair Barry Clegg said the 15-member panel, appointed by Hennepin County's chief judge, would decide next Wednesday whether to issue an opinion.

The commission's is normally tasked with reviewing amendments to the city's charter and overseeing the redistricting process.

“We don’t really have any specific authority to review or make binding decisions about whether the charter is applicable or not," Clegg said. "So this would be in essence asking our opinion, which would not be binding in any way.”

In an online posting, Clegg challenged several points of City Attorney Susan Segal's analysis -- which remains oral advice, rather than a formal written opinion.

The legal questions surrounding the charter could also be moot if the state includes superseding language nullifying portions of the charter. Council president Barb Johnson argues the nullification is necessary not for the stadium, but Target Center upgrades.