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As campaigns for 2014 gubernatorial races across the nation get off the ground, the issue of minimum-wage increases has gotten even more attention. Democrats vying to challenge a slew of Republican governors, particularly those seeking re-election in states that President Barack Obama won in 2012, have already started championing the cause.

Polls say it's publicly popular, it revives the message of economic inequality that Obama wielded effectively last year, and it comes wrapped in a broader jobs and economic message that touches on the top priority of many voting Americans.

In Pennsylvania, championing a minimum wage increase is already popular among the big field of Democrats vying to challenge the re-election bid of Republican Gov. Tom Corbett.

Now, Katie McGinty, a onetime environmental policy adviser to the Clinton White House and Corbett's Democratic predecessor, is distinguishing herself by telling audiences and potential donors that she was the first Democrat in the Pennsylvania field to make it an issue.

"This is core for me," McGinty said. "I think it is fundamentally true across the centuries that one of the things that can really bring a nation down is the increasing chasm in terms of income."

Thus far, the Republicans whom Democrats view as most vulnerable aren't changing their minds and supporting it.

In addition to Corbett, the Democrats' list of most vulnerable includes Maine's Paul LePage, Michigan's Rick Snyder and Wisconsin's Scott Walker.

Florida's Rick Scott and Ohio's John Kasich might be insulated because their states' laws boost minimum wage with inflation and Iowa's Terry Branstad, New Mexico's Susanna Martinez and Nevada's Brian Sandoval aren't viewed as sufficiently endangered.

All of those governors won a first term in the national Republican sweep of 2010, and most have had strong Republican representation in their legislatures to support them.

But LePage was tasked with facing a Democratic-controlled legislature, and in July he vetoed a bill to incrementally raise the state's minimum wage.

For his likely Democratic challenger, U.S. Rep. Mike Michaud, increasing the minimum wage is an issue the one-time paper mill worker from northern Maine discusses often, said campaign adviser David Farmer.

"He is closely aligned with working- and middle-class families," Farmer said. "He's not a millionaire."

Still, it would not be unheard of for a Republican to advocate a minimum wage increase. New Jersey Gov. Chris Christie, who leads the Republican Governors Association, and New Mexico's Martinez each vetoed their legislature's minimum wage bill but not without making a counteroffer of a more modest increase.

Republican governors are focused on lightening tax and regulatory burdens for businesses to improve wages, said Jon Thompson, a spokesman for the Republican Governors Association. But he also seemed to acknowledge the occasional political necessity for Republicans to embrace a minimum wage increase.

"It's complicated because there are some states that a minimum wage increase could be more helpful and useful than other states," Thompson said in an email.

For Democrats, campaign advisers and strategists say there's no mandate from national party leaders to wield the issue as a weapon next year. But there's no denying it's popular and salient to the political battlefield, said Danny Kanner, spokesman for the Democratic Governors Association.

"The defining issue in every single one of these races is who is fighting for the middle class," he said.