Wisconsin Democrats won control of the state Assembly Tuesday night, giving them control of both the state Legislature and the governor's mansion for the first time in more than two decades.

The switch could change the way the state responds to a deeply troubled economy and a projected budget shortfall of at least $3 billion. If they take the Assembly, Democrats have said they'll seek a tax on hospitals to fund health care and work to find money in a tightening budget for investment in education, renewable energy and manufacturing.

"There was a mandate from voters for change, and we're certainly going to be a catalyst for that," said Rep. Mark Pocan, D-Madison, who headed up Assembly Democrats' campaign efforts.

Going into Tuesday's elections, Republicans held the Assembly by a 51-47 margin with one independent, giving them a veto to proposals by Democratic Gov. Jim Doyle and the state Senate. Pocan said he was confident Democrats would see a net gain of at least four to five seats, enough to flip the house in their favor.

Assembly Speaker Mike Huebsch, R-West Salem, also said he expected to lose five seats, which could leave the chamber at 52-46 with one independent. Those losses included longtime incumbent Rep. J.A. "Doc" Hines, R-Oxford, who was unseated by Democratic challenger Fred Clark.

"There was just a tremendous wave of change that came through," Huebsch said. "Sometimes that's just insurmountable."

Democrats were expected to retain control of the Senate as of 1 a.m. today. Senate Minority Leader Scott Fitzgerald, R-Juneau, said he expected Republicans to retain 15 seats in the Senate, with Democrats controlling the chamber at 18 seats.

Fitzgerald said he expected Republican incumbents Sheila Harsdorf of River Falls, Dan Kapanke of La Crosse, and Alberta Darling of River Hills to hold their seats, while Randy Hopper was leading an open race in Oshkosh. Democrats held a narrow lead an open seat in northeast Wisconsin, Fitzgerald said.

Jeff Buhrandt, a spokesman for the Senate Democrats' campaign, said Democrat Jim Holperin, the former tourism secretary, won in that northeastern state seat and that Democrat Alison Page had conceded to Harsdorf. But Buhrandt said Democratic officials wanted to wait for additional returns before making other statements.

The Associated Press said Democratic State Rep. Sheldon Wasserman was leading Darling by about 3,000 votes with 83 percent of the precincts reporting. Holperin was ahead of challenger Tom Tiffany by about 1,300 votes with 94 percent of the precincts reporting. Kapanke was leading challenger Tara Johnson by about 5,700 votes with 85 percent of the precincts reporting. And Hopper was leading Democrat Jessica King by 2,400 votes with 89 percent of the precincts reporting.

According to early unofficial returns, Rep. Brett Davis, R-Oregon, defeated Democratic challenger John Waelti of Monroe in one closely watched race.

Unofficial returns also showed Republican Keith Ripp of Lodi narrowly defeating Democrat Trish O'Neil of Columbus, for another closely watched open seat. With all the precincts in, Ripp had 15,446 votes — just 28 votes more than O'Neil. O'Neil didn't immediately return a message asking whether she would seek a recount.

Rep. Jeff Wood, I-Chippewa Falls, defeated Republican challenger Don Moga by just 175 votes after a bitter contest that followed Wood's departure from the Republican party earlier this year.

Mordecai Lee, a professor of governmental affairs at UW-Milwaukee, said that he didn't believe Democrats winning the Assembly would have a "mandate for rigid ideological approaches."

Assembly Republicans campaigned by saying they'd block the higher taxes sought by Doyle and Democrats and keep state caps on local property taxes.

Democrats said they want to keep taxes lower for the middle class but also said they'd seek targeted tax increases to help balance the budget and pay for their priorities.

That includes a $416 million hospital tax, defeated by GOP lawmakers last year, which would have brought in $413 million more federal dollars to reimburse hospitals and help pay for Medicaid health care for the poor.

"If the Democrats are victorious, you're going to see us get to work right away on the economy and jobs," Pocan said. "The middle class in Wisconsin is definitely going to be at the forefront of our agenda."

Huebsch said a Republican loss in the Assembly could lead to an expansion in government taxes, spending and regulation by Democrats.

"What is at stake is the direction we're going to go with the state," Huebsch said. "It really does come down to the era of big government and will it come back?"

Lee, who served as a Democratic state Senator the last time that party had complete control of state government, said the difficult budget and national economy would make it hard for Democrats to push a new agenda.

There are at least a few significant policy changes that Democrats could make that wouldn't require new money in the budget. Those include passing a statewide workplace smoking ban that would include bars and restaurants and requiring insurers to cover the costs of autism treatment.

— The Associated Press and State Journal reporter Mark Pitsch contributed to this report.