Maybe, but $15 isn't going to happen everywhere soon. (AP Photo/Ben Margot, File)

From a distance, the movement for a $15 minimum wage can seem unstoppable. Seattle, San Francisco, Los Angeles  is there any liberal city that wouldn't vote to double the federal wage floor?

The answer is yes, advocates learned Tuesday. Portland, Maine  the state's largest city, leaning heavily Democratic  voted 58 percent to 42 percent against a ballot measure that would have raised the local minimum wage to $15 by July 2019 for most businesses, and sooner for those with more than 500 employees.

There are lots of reasons why the measure lost. The business community vastly outspent the mainly Green Party-backed ballot proposition  according to the Portland Press Herald, the funding advantage was about 100 to one. The idea also ran into liberal opposition: The director of the business campaign against the wage hike, Toby McGrath, had run President Obama's campaign in the state in 2008 and 2012.

But mainly, the city council had already voted to raise the minimum to $10.10 by next year; in a city with a median hourly wage of $17.32, $15 seemed like piling on.

"I think it was too much, it was too far a step for people," says Amy Fried, a political science professor at the University of Maine. "A lot of people felt like it made more sense to do something statewide, then you don’t have a whole situation where Portland is separate from the communities around it."

Maine will likely get that chance next fall, when advocates are planning to have a ballot measure that would raise the state's minimum wage to $12 by 2020  a more gradual increase from $7.50, where it is right now. The Maine Peoples' Alliance says that it's raised $150,000 already for the campaign, which will happen in a presidential election year, when turnout is usually highest. And a statewide poll out last month found 68 percent of respondents supported raising the minimum wage.

In fact, although the Portland measure failed during Tuesday's election, Maine Peoples' Alliance director Amy Halsted says that her 300 volunteers collected 30,000 signatures at the polls for the $12 statewide measure, giving them enough to officially qualify for the ballot.

"People were literally lining up to sign our petition," Halsted says. "So there is certainly a real appetite for raising wages." That campaign is also backed by the Fairness Project, a nationwide group supporting minimum wage ballot initiatives in several states in 2016, whether or not they're trying for the full $15.

Here's another indicator from Tuesday's elections. The city of Tacoma, Wash. was given a choice of raising the minimum wage not at all, to $12 over a couple years, or to $15 immediately. Framed that way, voters picked the middle option. In many cities, $15 an hour is really just an opening bid — advocates know they're going to get bargained down. Without starting high, they wouldn't have gotten even to $12 at all.

The important lesson: People might favor raising wages, but it matters how high.