Scott Walker inches ahead in Wisconsin governor's race

In this file photo, Gov. Scott Walker, R-Wis., speaks during the Republican Jewish Coalition spring leadership meeting at The Venetian Las Vegas on March 29, 2014 in Las Vegas, Nevada.

Ethan Miller, Getty Images

Embattled Republican Gov. Scott Walker of Wisconsin has added a little more cushion to his lead against his Democratic opponent, former Trek bicycle executive Mary Burke.

Walker wins 50 percent support among Wisconsin voters who say they are certain to vote this November, according to a new Marquette Law School Poll. Burke receives 45 percent support, while 3 percent are undecided and 1 percent say they'll vote for someone else.

The poll, conducted September 25-28, has a 4.1 percent margin of error. In prior polls in recent weeks, Walker's lead has been smaller than the margin of error.

Among registered voters (including those not certain to vote), the race is much closer -- Walker wins 46 percent while Burke wins 45 percent.

In a Marquette poll conducted in mid-September, Walker held a three-point lead among those certain to vote. Meanwhile, in early September, the CBS News/New York Times/YouGov Battleground Tracker showed Walker is up 49 percent to Burke's 45 percent.

Walker was one of several Republican governors swept into office in the 2010 tea party wave. He enacted several controversial reforms, such as a bill outlawing collective bargaining for public employee unions in 2011.The move sparked a recall effort in 2012, but Walker prevailed.

The latest Marquette poll shows a clear gender divide. Among likely voters, Walker leads among men, 62 percent to 34 percent. Among women, Burke leads, 54 percent to 40 percent.

Both candidates seem to have taken a hit from recent bad press. As many as 54 percent of registered voters said they've heard about reports that the Burke campaign copied portions of its jobs plan from other Democratic campaigns. As many as 18 percent said the story made them less likely to vote for Burke.

Meanwhile, 53 percent said they've heard that Wisconsin is ranked 33rd of 50 states in job creation. As many as 26 percent say they're less likely to vote for Walker because of this.

Both candidates have recruited high-profile politicians to help them on the campaign trail. New Jersey Gov. Chris Christie recently campaigned with Walker, while first lady Michelle Obama campaigned for Burke.

The Marquette poll also showed that 63 percent of registered voters are in favor of a new law requiring a government-issued photo ID in order to vote, while just 33 percent oppose it. A federal appeals court ruled last month that the state must enforce the law in November's election, though opponents of the law are asking the Supreme Court to keep it from being enforced.