Walker has been a lightning rod for partisans on both sides of the aisle since pushing through controversial legislation restricting state workers' ability to unionize, prompting mass protests in Wisconsin last year.

Many are looking to the June 5 election as a proxy battle for Republican austerity efforts, and as a measure of union influence in 2012. Labor has poured substantial resources into Walker's defeat, while conservative political action committees have also proven aggressive in the state.

But the poll showed that Wisconsin voters might be wary of union efforts. Only 35 percent of respondents said they had a favorable opinion of public-sector unions, versus 31 percent who said they had an unfavorable opinion. More than half of those surveyed also signaled support for increasing the amounts government employees contributed to their healthcare and pensions.

The poll found that 44 percent said public employee unions have too much power in negotiating their contracts, and a plurality said public-sector unions have done more to hurt than help local economies.

In the presidential race, President Obama holds a comfortable lead over presumptive Republican challenger Mitt Romney, winning the state 46-36 percent among likely voters. Some 6 percent chose Libertarian Party nominee Gary Johnson as their top presidential choice.