The latest Marquette University poll released Wednesday shows Gov. Scott Walker with a 46%-45% lead over challenger Mary Burke.

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Dead heat.

That's what Wisconsin is staring at in the race for governor, with Gov. Scott Walker and Democratic challenger Mary Burke neck-and-neck heading into the November election, according to the latest Marquette University Law School poll released Wednesday.

Among registered voters, Walker led Burke, 46% to 45%. Among likely voters, Burke led Walker, 47% to 46%.

"The bottom line is that nothing has statistically changed from May to July," said Charles Franklin, the poll director. "We're seeing a dead heat in the race, well within the margin of error."

"As the race really heats up with advertising and back and forth, I'd expect to see interesting developments over the next months," he added.

In the May sample, the race took shape as the Republican incumbent was first deadlocked with Burke, a member of the Madison School Board. The two candidates recorded 46% each, with 6% undecided. Back then, Walker led Burke among likely voters by 48% to 45%.

The new numbers suggest a long hot summer on the campaign trail, with more television advertising and even more intensive get-out-the-vote efforts by the campaigns.

Walker, a potential GOP presidential candidate, now finds himself in a tossup against a challenger in her first statewide race.

At an appearance in Madison, Walker said he always expected the race to be close, but believed his supporters' willingness to make phone calls and knock on doors would secure his re-election.

"We believe in the end the grass roots will make the difference," Walker said.

At an appearance in Milwaukee, Burke said she was encouraged by the poll and that over the next 31/2 months she will work to raise her profile so that people get to know her.

"I'm very glad to be out ahead in terms of likely voters for the first time," Burke said.

Here are five take-aways from the poll.

Voters don't know Burke

Burke has been on the campaign trail for months, but 49% of those polled said they don't know enough to form an opinion about her. Of those who could, 26% had a favorable view of her and 24% had an unfavorable view.

The race to define Burke is now in full swing. She has gone up on television with a biographical advertisement playing up her business credentials and her family's firm, Trek Bicycle Corp. In contrast, Walker has launched ads attacking Burke for profiting from Trek's outsourcing of jobs to low-wage China.

"When the race itself is a topic on the front page and at the lead of every newscast, we're going to see the public come to much greater awareness of her," Franklin said. "Certainly by the fall, the vast majority of voters will know who she is."

They know Walker

Facing his third election in four years, Walker has a 47% job approval rating, against 48% disapproval. He is viewed favorably by 45% and unfavorably by 47%. And when asked if "able to get things done" described the governor, 66% said it did while 29% said it did not.

Walker doesn't appear to be getting a boost from voters' views on how the state is doing. Fifty-four percent said Wisconsin was heading in the right direction and 41% said it was on the wrong track.

Seventy-five percent said they have heard something about the John Doe investigation into political allies of Walker, while 24% had not. Among those who knew about the investigation, 54% said the John Doe probe was just more politics, while 42% said it was serious.

Coalitions are key

No surprise, 93% of Republicans back Walker. But only 88% of Democrats back Burke, with 9% saying they will vote for Walker. Burke, however, has cut into Walker's lead among independents. In May, this coveted group went 49% to 40% for Walker. In July, Walker had 45% of independents to 44% for Burke.

Women backed Burke by 48% to 41% while men backed Walker by 51% to 41%.

Married voters supported Walker by 54% to 38%. In a demographic breakdown, Walker's strongest support came from those ages 45 to 59, where he led 51% to 42%.

Among those who never married, Burke held a 53% to 34% advantage. She led 53% to 38% among those widowed, divorced or separated. Her strongest demographic was among voters ages 18 to 29, where her lead was 48% to 35%.

Voter contacts on rise

Watch your doors, your phones and your mailbox, the campaigns are coming. A third of those surveyed said they have been contacted by one of the political parties or campaigns in the past month. Fifty-three percent said both parties contacted them, 14% said just Democrats reached out to them while 25% said only the Republicans contacted them.

"All of the developments over the last 10 days certainly promises a much more active campaign period from now through the fall," Franklin said.

Money and marriage

There's still support for raising the minimum wage from $7.25 an hour, with 56% backing an increase and 39% opposed. In March, 63% supported an increase and 33% were opposed.

More than a month after a federal judge struck down the state's constitutional ban against gay marriage, 56% said they would repeal the ban if they could while 37% would vote to keep it.

The poll of 804 registered Wisconsin voters was conducted by interviews on cellphones and landlines Thursday through Sunday. The margin of error was plus or minus 31/2 percentage points.

Among those polled were 549 people who said they were registered and likely to vote. The margin of error on that sample was 4.3%.

Jason Stein and Patrick Marley of the Journal Sentinel staff contributed to this report.