Hennepin County Board Chair Mike Opat is telling legislative leaders that the county board opposes using excess revenues from the county's ballpark tax to backstop state funding for a new Vikings stadium in Minneapolis.

In a strongly-worded letter sent Monday afternoon to Senate Majority Leader David Senjem and House Speaker Kurt Zellers, Opat said the county's 0.15 percent sales tax was approved by both the board and the Legislature in 2006 only for specific "permitted uses."

"Now, absent any consultation with members of the Hennepin County Board, the House bill would take the unprecedented step of effectively hijacking county revenue should charitable gaming revenue fall short," Opat wrote.

He asked Senjem and Zellers to remove the provision from the stadium bill.

Most of the revenue from the sales tax goes to pay down the debt on Target Field. An additional $4 million a year is used to make grants for youth sports programs and to extend library hours; any additional revenue goes to the ballpark.

The stadium bill before the House includes four funding backstops, including Hennepin County, that might be used if electronic pull tabs and bingo failed to generate an estimated $42 million needed each year to pay the state's $398 million share of a Vikings stadium.

In his letter, Opat said the bill would extend the tax without getting approval from the board and "breaks faith" with county commissioners, who partnered with the state in 2006 to build Target Field. Although the state didn't help fund the ballpark, Hennepin County needed state approval to levy the local sales tax.

In an attached analysis of the bill proposal, assistant county attorney Daniel Rogan wrote that it would be "unprecedented" for the Legislature to change the use for local tax revenue without local approval.

Rogan said a strong case could be made that such an act would violate the Minnesota Constitution because the tax would be collected from one jurisdiction to pay for a general state obligation.

The stadium bill will go before a House committee Monday evening.