Wisconsin Republicans have provoked uproar by limiting the power of a newly elected Democratic governor.
If signed by outgoing Republican Governor Scott Walker, the bills will curb the authority of incoming Democrat Tony Evers and his attorney general.
Protesters have been demonstrating at the state capitol in Madison for days, accusing Republicans of trying to rig the system.
But state Republicans say the bills only seek to balance power.
In the neighbouring Midwestern state of Michigan, another Republican-controlled legislature is considering the passage of similar laws to hobble newly elected Democrats.
The controversy mirrors what took place in North Carolina in 2016 after an incumbent Republican governor was defeated by a Democrat.
In a nine-hour, all-night session that began on Tuesday, Wisconsin Republicans in the state Senate pushed through a number of proposals that would limit the governor and attorney general roles.
The party lost both positions to Democrats in the mid-term elections on 6 November.
If Mr Walker approves the bills – and he has indicated support for the measures – his successor will be forced to seek permission from the legislature before seeking changes to various programmes.
Furthermore, the bills limit the governor’s ability to address early voting and voter ID laws.
These are crucial provisions in a presidential swing state that President Donald Trump only narrowly won in 2016.
And the attorney general would no longer have the ability to remove the state from federal lawsuits.
That power, along with others, would go instead to the state legislative branch, still Republican-dominated.
It would prevent Mr Evers and attorney general-elect Josh Kaul from making good on campaign promises such as removing the state from a lawsuit against the Obama-era Affordable Care Act.
The state Senate approved 81 people for boards, authorities and councils during the same overnight session.
Governor Walker also approved a judge and two district attorneys.
Protesters were cleared from the Senate galleries just after the session began. They chanted: “Shame!”
In a statement on Wednesday, Mr Evers said “power-hungry politicians” had pushed the changes through to “override the will of the people of Wisconsin who asked for change”.
But Republicans say the changes are blown out of proportion and ensure Wisconsin’s government is evenly balanced.
Republican Robin Vos, Speaker of the Wisconsin State Assembly, said on Twitter that “Democrats have been exaggerating and resorting to hyperbole”.
“The vote is about ensuring equal branches of government exist in Wisconsin, especially during this time of divided government.”
Democrats countered that the other party made no such objection when a Republican governor was in power.
Republicans have controlled Wisconsin for eight years.
Mr Evers won the gubernatorial race against Mr Walker by a margin of less than 30,000 votes.
If the bills are challenged via lawsuits, the government could face gridlock next year.