The Democratic Party lost its majority in the state Senate Tuesday night after Republicans picked up two seats that gave them control of the body, the Assembly and governorship for the next legislative session.

According to The Associated Press’s preliminary results, Rep. Tom Tiffany, R-Hazelhurst, defeated Democrat Susan Sommer 57 percent to 40 percent in the race to fill the seat of retiring Sen. Jim Holperin, D-Conover.

Republican Rick Gudex may have also won a seat in the Senate, receiving 43,039 votes to the 42,449 votes incumbent Sen. Jessica King, D-Oshkosh, received, according to preliminary counts by The Associated Press. However, The Associated Press had not declared Gudex winner of the seat by press time.

Currently, the Democrats hold a 17-15 majority in the Senate after Sen. John Lehman, D-Racine, won a recall election against former Sen. Van Wanggaard, R-Racine, and former Sen. Rich Zipperer, R- Pewaukee, resigned in July to work for Gov. Scott Walker’s administration.

While Walker ordered a special election to fill Zipperer’s seat on Dec. 4, no Democrats have entered the race or met the filing deadline for nomination papers in the district, according to the Government Accountability Board’s website.

Common Cause in Wisconsin Executive Director Jay Heck said in light of the re-election of President Barack Obama and the election to the U.S. Senate of U.S. Rep. Tammy Baldwin, D-Wis., Republicans should not consider winning the state Senate as a mandate to pursue policies that further divide the state.

Heck said Republicans must make a decision in the coming months to cooperate across party lines in the coming legislative session.

“I think that’s tonight’s lesson,” Heck said. “This election tells us that Wisconsinites are tired of extreme partisanship and should come together and solve problems rather than pursue in-your-face politics.”

Voters want Walker and Republican legislators to work with Democrats to solve the state’s problems, Heck said.

Wisconsin Democracy Campaign Executive Director Mike McCabe said Senate Democrats also faced an uphill battle because of the Republican-controlled Legislature drawing district lines in the past legislative session.

“Districts were redrawn [by Republicans] in a way to give them a bigger edge in more districts,” McCabe said. “It was clearly Republican gerrymandering, and it clearly made it easier for Republicans to win.”

McCabe also said Democrats faced a fundraising challenge, as many Republicans outraised and outspent them.

McCabe said big donors typically give to both campaigns to “hedge their bets” and ensure they have an investment in the winner. However, McCabe said these donors gave more to Republican candidates for this election cycle than Democrats.

“Money flows to power,” McCabe said. “It seems to us big donors are betting on Republican control of the Senate because more money is flowing into their campaigns.”

According to the Wisconsin Democracy Campaign website, Republican candidate Tiffany outraised Sommer by about $200,000 and outspent her by $150,000.

While the average state Senate campaigns have become more expensive, none of the state Senate campaigns this year broke the 2011 record for spending, where one competitive Senate district in a recall election saw parties spending more than $10 million.

However, McCabe said a few Senate campaigns may spend more than a million dollars this election cycle.

The Associated Press contributed to this story.