By Andy Sullivan

WASHINGTON (Reuters) - President Barack Obama's push to raise the minimum wage, which has largely found success in liberal-leaning coastal states to date, could make headway in the conservative heartland in the November elections.

Voters in the Republican-controlled states of Alaska, Arkansas, Nebraska and South Dakota will consider ballot initiatives in November that would raise the minimum wage above the national rate of $7.25 per hour. Activists on both sides of the issue say the proposals stand a good chance of passing.

If successful, the ballot measures would provide further evidence that the idea of raising minimum pay has support across party lines. A favorable outcome could also turn up the heat on Congress to raise the national rate. Obama proposed raising the national minimum to $9 per hour in his 2013 State of the Union address and now advocates for a national minimum of $10.10. But the idea has gained little traction among Republicans who control the House of Representatives.

Congress last voted to raise the national wage in 2007 following successful ballot initiatives in Arizona, Colorado, Missouri, Montana, Nevada and Ohio. Since last year, some 13 states and six cities, largely controlled Democrats, have raised their own minimum wages. In Seattle, the minimum wage will gradually rise to $15 an hour by 2021, the nation's highest rate.

"State and local momentum is what drives Congress to ultimately follow suit, and 2014 has really laid the foundation," said Jack Temple, a policy analyst at the left-leaning National Employment Law Project.

THE END AROUND

The ballot initiatives allow labor unions, charity groups and Democrats a way to boost wages in states where Republican-controlled state legislatures have been reluctant to act. Voters haven't rejected a minimum-wage hike at the ballot box since 1996 and have approved 13 raises in conservative and liberal-leaning states since then, according to the Ballot Initiative Strategy Center.

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In 2013, for instance, voters in New Jersey passed an increase to $8.25 per hour after Republican Gov. Chris Christie vetoed an increase that had passed the legislature.

Lawmakers in Massachusetts, Minnesota and Michigan opted to raise the minimum wage this year to head off ballot initiatives in their states. Voters in Democratic-controlled Illinois will weigh in on a non-binding proposal in November as well.

Business groups have successfully lobbied against a minimum-wage increase in Congress and many state legislatures by arguing that it would slow job creation and raise costs. That's a tougher sell when talking directly to voters.

"It's other people's money - it's easy to spend," said Denny DeWitt, who is leading the fight against the minimum-wage hike in Alaska as state director of the National Federation of Independent Business.

SAVING THE SENATE

The ballot questions could also boost Democrats' chances of holding on to the Senate in November by drawing in low-wage workers who otherwise might sit out the election.

Just as Republicans used gay marriage ballot initiatives to drive up turnout among religious conservatives in the last decade, Democrats now aim to boost turnout with the minimum wage question, said Jennifer Duffy, an analyst with the nonpartisan Cook Political Report.

Geoff Holland is a good example. A janitor in Lincoln, Nebraska, Holland heard about the ballot initiative to raise the minimum wage in his state to $9 an hour during a visit to a food pantry. Though he does not usually participate in politics, Holland said he plans to vote for the measure this fall. "It has to be done," said Holland, who earns $8 per hour. "The price of everything else goes up and the wages don't go up."

Omaha, Nebraska waitress Sonia Bentley, a self-described political independent, says she doesn't support Democratic priorities like expanding Medicaid health coverage for the poor. But her opinion of Republican officeholders has soured since she began advocating for a minimum wage hike.

Holland and Bentley aside, the ballot questions aren't exactly a slam-dunk for the Democrats. For instance, they may not help Democratic Senate candidates in South Dakota and Nebraska, where Republican candidates are heavily favored.

But the proposal could make a difference in Alaska, where incumbent Sen. Mark Begich faces a tough re-election battle. The AFL-CIO labor union, which backs Begich, is making the minimum-wage ballot question a core part of its message in door-knocking and phone calls to voters. Voters in that state also will consider a proposal to legalize marijuana, another measure that could help Democrats.

Alaska Republicans who control the state legislature, in fact, tried to raise the state minimum wage this spring. But they were blocked by Democrats and their allies who wanted to put the question directly to voters instead.

The proposal would raise the state's minimum wage from $7.75 to $9.75 by 2016 and adjust it for inflation after that.

In Arkansas, both Democratic Senator Mark Pryor and his Republican challenger, Tom Cotton, back the ballot proposal that would gradually raise the state minimum wage to $8.50 an hour by 2017.

A poll this spring found that nearly 8 in 10 Arkansas voters supported the raise. That's a sign that many voters in one of the nation's poorest states know someone personally who is struggling to make ends meet on minimum wage, said Steve Copley, a Methodist minister who chairs the advocacy group Give Arkansas A Raise Now,

The minimum-wage push could help Pryor by drawing in otherwise ambivalent Democratic voters like Jennifer Nelson, who works two minimum-wage jobs as a home health aide and day care worker.

"I don't dislike him or like him," Nelson said of Pryor. The ballot proposal, on the other hand, "would make a big difference. I'd have a little extra money. I'd try to save it."

THE BOTTOM LINE

If successful, the ballot initiatives would boost wages for 419,000 workers, says the National Employment Law Project. That's on top of the 7 million workers who will benefit from the other state and local increases passed over the previous two years, but still far short of the 28 million workers that the White House estimates would benefit from a national $10.10 rate.

But it's unclear if the White House will ultimately benefit. Advocates of the four ballot initiatives are eager to put distance between their efforts and those of a president who has little support in their states. In Nebraska, advocates say their low cost of living and conservative-leaning electorate prompted them to settle on a target of $9 an hour by 2016.

"We definitely took pains when crafting the measure to ensure that it was right for Nebraska," said Democratic State Sen. Danielle Conrad. "We weren't just blindly following a national trend."

(Editing by Caren Bohan and Hank Gilman)