MADISON, Wis. (AP) — The Wisconsin Supreme Court will hear a case on Wednesday that pits Democratic Gov. Tony Evers against the Republican-controlled Legislature in a fight that could have a broad impact on how state government functions.

The case marks the latest power struggle between the Legislature and Evers, who has issued more vetoes than any Wisconsin governor. A ruling in favor of Evers would upend decades-old practices in the Legislature and make it easier to approve projects in a land stewardship program. But Republicans warn that the dispute is about much more than that.

Evers argues that the Legislature’s powerful budget-writing Joint Finance Committee, controlled 12-4 by Republicans, is exceeding its constitutional lawmaking authority and acting as a fourth branch of government. The Legislature counters that the committee’s powers, including the approval of certain state conservation projects, are well established in state law and court precedent.

The Legislature’s attorneys argue in court filings that Evers is seeking a “fundamental shift” in the state’s governmental structure. If the court sides with Evers, then numerous other functions of the budget committee, the state building commission and other legislative committees would also be unconstitutional, the GOP attorneys contend.

Evers, speaking about the case on Tuesday, said the state Supreme Court needs to recognize that the Legislature’s budget committee has been acting as a fourth branch of government and should be reined in.

“The idea that somehow they have the ability to essentially work as a fourth arm of our state is just wrong,” Evers told reporters.

The lawsuit cites the committee’s rejection of dozens of conservation projects selected by the Wisconsin Department of Natural Resources under the Knowles-Nelson Stewardship Program.

The Legislature created the stewardship program in 1989. It provides funding primarily to local governments, conservation groups and the DNR to purchase blocks of land to preserve natural areas and wildlife habitat, protect water quality and fisheries, and expand outdoor recreational opportunities. Supporters herald it as a way to further protect natural areas from development.

Republicans have been trying for years to scale back stewardship purchases, complaining that they take too much land off the tax rolls, rob northern Wisconsin municipalities of revenue and drive up state debt.

Legislative oversight of the program increased as concerns grew about the scope and cost of the stewardship program.

The Legislature did its job when it passed laws creating and funding the program, attorneys for Evers argue in court filings. But the budget committee’s ability to block approval of stewardship projects, essentially vetoing decisions of the executive branch, is an unconstitutional separation of powers violation, they say.

Evers’ lawyers are calling for the court to “restore the constitutional balance of power to our state government.”

But the Legislature’s attorneys counter that it would be “a grave separation-of-powers insult” to “undercut these decades-long systems now, allowing agencies to have unchecked authority.”

The court will issue a ruling in the next several weeks or months.

Evers brought the case in October, two months after the court flipped to majority liberal control. The case is one of several high-profile lawsuits filed by Democrats since the court’s majority changed.

Most significantly, the court in December struck down Republican-drawn legislative maps, which led to the Legislature enacting maps drawn by Evers that are expected to result in more Democrats winning seats in November.