"We must look at the wonderful job our great governor Scott Walker has done for us, and the people in the state of Wisconsin were wise enough to return to him a majority in our state Senate," Attorney General J.B. Van Hollen told dejected Thompson backers at what supporters had hoped would be a victory party.
What Republicans do with their reclaimed majority remains to be seen. Legislative leaders and Walker have been vague in describing their agenda for the next two years.
There was no change to the makeup of the state's U.S. House delegation. Five Republican incumbents, including Romney running mate Paul Ryan, and Democrats won re-election. State Rep. Mark Pocan, a Democrat, won the race to replace Baldwin in her Madison-area congressional district.
Wisconsin's gay community heralded the wins of both Baldwin and Pocan, who also is openly gay.
"This is truly a historic night for the lesbian, gay, bisexual and transgender community," said Katie Belanger, executive director of Fair Wisconsin, the state's largest gay rights group.
Republicans were also buoyed by Ryan's ascendance after being picked as Romney's running mate, even though it ultimately was a losing effort. The longtime congressman is already being discussed as a possible presidential candidate in 2016.
About half of those surveyed in an Associated Press exit poll said they had a favorable opinion of Ryan, including one in eight who said they voted for Obama. Four in 10 said they had an unfavorable view of Ryan.
Tuesday's election caps off a wild two years in Wisconsin, first with the fight over Walker's collective bargaining law, then the multiple recall elections targeting state senators and Walker, followed by Ryan's rise and the state's central role in the presidential campaign.
While Republicans scored the most significant victories during the past two years, Democrats savored the reversal of fortunes brought by their wins Tuesday.
"It has been a tumultuous two years in Wisconsin as we have engaged in this great conversation over the future and values of our middle class," Tate, the Democratic Party chairman, said in a statement. "We know and feel deeply that change can be difficult — but as Senator-elect Baldwin's and the president's victory tonight proves — it will come."
Follow Scott Bauer on Twitter at http://twitter.com/sbauerAP .