Bernero had the support of 40 percent of participants in the poll, which was released Wednesday. Dillon had 32 percent. About 28 percent of voters at that time still were undecided.

The Democratic poll was conducted July 24-26 and the GOP poll was conducted July 26-27. Both used a live telephone interview with 400 voters statewide, and the margin of error is 4.9 percent.

In EPIC-MRA’s previous poll, conducted in June, Dillon carried 34 percent of respondents. Bernero pulled in 24 percent of voters in the same poll. About 42 percent of voters were undecided.

Republicans are more split as to which candidate would make the best governor. Snyder carried 26 percent of the vote in the poll, which was released Thursday. Cox had 24 percent and Hoekstra netted 23 percent. Behind the pack, Bouchard obtained 10 percent and George had 1 percent.

In EPIC-MRA’s June poll, Cox and Hoekstra were locked in a statistical tie with 26 percent and 24 percent support, respectively. Snyder came in a close third with 20 percent support, but since has gained ground.

Bernero’s recent success likely stems from the support of independent organizations, such as the Genesee County Democratic Committee, which has spent about $1 million on pro-Bernero advertising, said Bernie Porn, the president of EPIC-MRA.

“That ad established a lot,” Porn said. “It also contrasted (Bernero’s) record in terms of creating jobs, as his campaign would claim, as opposed to Dillon cutting jobs in the private sector and cutting pay. Also, they added a feature on the ads that contrasted Dillon and Virg Bernero on the abortion issue.”

Voters are paying attention to Bernero’s message to fix Michigan, campaign spokesman Jamaine Dickens said in an e-mail.

“Michigan voters are keenly aware that their state government is broken,” Dickens said. “Voters are supporting Virg Bernero’s call to shake things up and get state government on the side of working families and not continue as the tool of the wealthy and well connected special interests.”

A spokesman for Dillon referred to press release statements about the candidate’s poll numbers and declined further comment.

“During the course of this campaign, we have seen poll numbers rise and fall,” Dillon spokesman T.J. Bucholz said in the statement. “The latest numbers don’t affect the basic choice next Tuesday. … We believe that Democratic primary voters will choose Dillon’s independence and bold ideas over Bernero’s divisive, old-style politics.”

Although Bernero likely will be the victor, turnout could change the final Democratic election results, Porn said.

“If it is a low-turnout election, that favors Bernero,” Porn said. “If it is a high-turnout election, then indeed it will be closer. I think Dillon has a difficult task in front of him to overtake Bernero at this point, unless something dramatic happens.”

On the GOP side of the election, turnout will mean everything, Porn said.

“The lower turnout would favor Hoekstra, because among those who are most certain to vote, he leads, and among those who always vote in Republican primaries, he leads,” Porn said. “It’s possible that if it’s a moderate type of turnout, (Cox) would win. If it’s a really heavy turnout, then Snyder would win, because he’s supported by more moderates and independent-type voters. … My guess is they will divide up the undecided (voters) and it will be a photo finish.”

Read Tuesday’s edition of The State News for a primary election voting guide.