Wisconsin’s embattled Republican governor, Scott Walker, has defeated an effort by labor unions and Democratic activists to end his tenure early, according to early results and exit polls.

The state has been a center of political controversy for more than a year – ever since Walker pushed a bill through the Legislature that sharply limited collective bargaining rights for teachers and most other government workers. Public employee unions led an effort to oust him, and early this year turned in more than 900,000 signatures on petitions, setting up only the third recall election of a governor in U.S. history.

But Walker fought back, arguing that he had made the “tough choices” needed to balance the state’s budget and free school districts from excessive costs. He also raised about $30 million, using a feature of the state’s recall law that allowed him to take unlimited contributions from supporters, many of them from out of state. Outside groups on both sides have poured money into the state, making the recall by far the most expensive race in Wisconsin history.

With more than $60 million spent overall, Walker and groups supporting him have had close to a 3:1 financial advantage over groups supporting the Democratic candidate, Milwaukee Mayor Tom Barrett.

Strategists in both parties have anxiously watched the recall election for signs of what might happen in the general election this fall. In 2008, Barack Obama carried the state by a large margin en route to winning the presidency. But in 2004, Wisconsin had one of the nation’s closest contests. The state is considered a must-win for Democrats.

Current polls indicate that Obama has a lead in the state, but a substantial amount of Walker’s money went into building a get-out-the-vote operation that also will benefit Republicans in November.