The Fight for 15 aims to get some traction on the campaign trail. In this photo, low wage workers and supporters protest for a $15 an hour minimum wage on November 10, 2015 in New York, United States. Getty Images/Spencer Platt

BROOKLYN, New York -- Shantel Walker has walked off her job at Papa John’s restaurant nine times in the past three years. This time, though, it felt a little different.

In September, the New York State labor commissioner approved a phased-in wage hike for all fast-food workers statewide, lifting the sector’s minimum wage to $15 in New York City by 2019 and in the rest of the state by 2021. That’s a major boost to people like Walker, who says she works about 36 hours a week, earning $9 an hour -- or 25 cents above the current pay floor.

“I always knew we would win,” says Walker, raising her voice above the sound of drums and chants from the protest march nearby. “But we don’t want to just raise the bar for us fast -food workers; we want to raise the bar for everyone. We want $15 across the board, across the country, for every worker.”

And they want union representation, too -- for workers in fast food, home care, retail and others in the low-paying service sectors. “It’s about having benefits and being secure,” says the 33-year-old Walker.

She doesn't have a preferred presidential candidate, but says "our vote will go to the candidate who stands behind the Fight for 15." "I don't care who's running for what: If they're not doing what I want and what I need, I'm not gonna vote," she says. "If the candidate endorses what we want, they're going have the fast-food workers' vote."

Protesters hit the streets Tuesday -- a full year before Election Day 2016 -- in a move designed to pressure presidential candidates to embrace the movement’s twin demands of $15 and union representation. The early-morning march in Brooklyn kicked off the latest round of nationwide demonstrations held by the so-called Fight for 15, the low-wage workers’ protest movement backed by the Service Employees International Union (SEIU). Since the movement was launched three years ago, several cities including Los Angeles, San Francisco and Seattle have passed major wage increases and a number of states have followed suit.

“This is a voting bloc that can’t be ignored,” says Mary Kay Henry, president of the SEIU. “We’re sending a message that’s loud and clear that we want elected officials to support people who are standing up for themselves and making this demand.”

Minimum Wage by State | InsideGov

The union, which has spent millions bankrolling the protests, points to a recent poll from the left-leaning National Employment Law Project. It found 69 percent of unregistered voters said they would register to vote if there were a candidate who supported “$15 and a union.” Meanwhile, 65 percent of registered voters earning less than $15 said they would be more likely to vote if there were such a candidate.

Other polls show public support for raising the minimum wage in general.

Are The Candidates Listening?

Sympathetic White House aspirants can be hard to find, especially among Republicans.

Most Republican presidential candidates say they wouldn't raise the federal minimum wage, which now stands at $7.25 an hour. Some -- like Jeb Bush -- have said they oppose the concept altogether.

Of the GOP contenders, only Ben Carson and Rick Santorum have expressed support for wage increases. The former, an outsider who recently overtook Donald Trump in some national polls, has not offered a specific figure. The latter, a former senator from Pennsylvania who polls in the low single-digits, supports raising the federal minimum by 50 cents over the next three years. Neither campaign responded to request for comment about the protests.

One of Tuesday’s high-profile demonstrations is slated to take place outside the Republican presidential debate in Milwaukee. A spokeswoman for the Republican National Committee did not respond to a request for comment.

Joseph McCartin, a labor history professor at Georgetown University, says he doubts demands to hike pay will get much traction among Republican primary candidates. “I think too many people on that side are worried about having somebody to their right and breaking with the orthodoxy.”

That could change as the general election nears.

“Once a Republican nominee is chosen, my reading is that person is going to have to moderate a bit on the question of wages,” McCartin says. “You look at what happened in some Republican states in the past cycle where Republicans swept to office but minimum wage hikes were enacted by referendum… Republicans are not necessarily going to want wages front and center as an issue differentiating themselves from Democrats.”

In 2014, Alaska, Arkansas, Nebraska and South Dakota --all states that preferred Mitt Romney to Barack Obama in the last presidential election-- passed ballot initiatives to increase their states’ minimum wages. (Voters in Nebraska and South Dakota also elected Republican candidates for U.S. Senate on the same 2014 ballot.)

Protesters with the Fight for 15 march in downtown Brooklyn, November 10, 2015. Cole Stangler

Among those seeking the Democratic nomination, both Bernie Sanders and Martin O’Malley support a $15 federal minimum. Frontrunner Hillary Clinton has praised some of the hikes to $15 an hour -- such as the ones in New York or Los Angeles -- but has declined to endorse a $15 figure nationwide.

SEIU President Mary Kay Henry seems undeterred. The union is widely expected to endorse Clinton, seen as the best option for defeating a presumptive Republican nominee who is likely hostile to organized labor. Henry did not say that Clinton should support $15 an hour, but praised the Secretary of State for publicly backing some of the recent pay hikes and cheered her broader commitment to union rights.

Many of the activists under the Fight for 15 umbrella are more enthusiastic about Sanders’ candidacy.

“$15 and a union is part of his platform,” says Carmen Hulbert, 65, a retired journalist, who was passing out flyers for Latinos for Bernie at the protest in Brooklyn. “He fights for the working class.”

‘It’s Upped The Ante’

More broadly, the demonstrations underlined the ongoing strength of a movement that began as a tremendous financial and political gamble from the SEIU -- and, to a large extent, still is. In the last year alone, the union spent $24 million on the Fight for 15 campaign, according to filings with Department of Labor.

“I think what the union has come to think -- and I think they’re absolutely right on this -- is if they continue to do business the way business is done, if labor continues to go in the same patterns it has in the last decade, a decade from now, it’s gonna be too weak to really move the needle,” says McCartin.

Today, less than 7 percent of private-sector workers are members of unions -- down from about a quarter in the early 1970s. Meanwhile, an upcoming Supreme Court case could put a dent into organized labor’s strength in the public sector strength by eliminating the ability of public sector unions to collect dues from non-members.

The Fight for 15 has managed to help notch pay increases in states and major cities, including Los Angeles, Seattle and San Francisco. But other than those policy victories, Ruth Milkman, a sociologist and labor movement expert at the City University of New York, says the protests have managed to shift the national discourse on low-wage work.

“I think the biggest success is making $15 the number that everybody has to relate to somehow,” says Milkman. “They many not support it, but they have to justify it if they’re taking a different number as some have. It’s upped the ante in a very dramatic way.”