Supporters of a $15 minimum wage rally on Wednesday outside the U.S. Capitol, where Democratic candidate for president Sen. Bernie Sanders (I-Vt) introduced a dead-on-arrival bill to raise the national minimum wage to $15/hour. (Kevin Lamarque/Reuters)

A historic measure to raise the District’s hourly minimum wage to $15 is headed toward next year’s ballot after city officials released a ruling Wednesday approving a voter initiative that places the nation’s capital at the center of a wage fight taking place in cities across the country.

If approved, the initiative would lift Washington’s minimum wage above every other city’s on the East Coast. It would push the District into a burgeoning, urban liberal vanguard on higher wages that includes Seattle, San Francisco and Los Angeles.

The ballot measure will go to voters in November 2016 only if supporters collect enough signatures, but even opponents say that is likely. It is one of several efforts moving ahead across the nation; also Wednesday, a state panel in New York approved raising the hourly rate to $15 for fast-food workers.

The day’s developments show that organized labor groups continue to gain ground rapidly on the issue, roiling pro-business groups and prompting a heated debate among both Republican and Democratic candidates for president.

Supporters of a proposed ballot measure to increase the District's minimum wage to $15-per-hour rally in April on Pennsylvania Avenue. (Aaron C. Davis/TWP)

In D.C., the minimum wage is $10.50 and is scheduled to rise to $11.50 next year. If the initiative passes, the new $15 hourly rate would raise a full-time worker’s annual pay to more than $31,000, up from the current minimum of about $22,000.

In one of the most expensive cities in the nation, where the median monthly rent for a one-bedroom apartment is $2,000 and where studies show that wage disparities are among the largest in the nation, the boost is not an unaffordable luxury but a necessity of survival, advocates say.

“People should not work a full-time job and live in poverty,” said Delvone Michael, director of the D.C. chapter of the Working Families Party, part of a group of labor unions and other progressive groups backing the measure.

Business groups warned that such measures would jeopardize jobs and cause businesses to close. The National Restaurant Association, which formed a group called Save NY Restaurants to try, unsuccessfully, to push off Democratic Gov. Andrew M. Cuomo’s plan to raise wages, warned of layoffs, automation and worse.

“Fifteen dollars is going to change the way restaurants do business,” said restaurant association spokeswoman Christin Fernandez. “They are going to be forced to cut labor, to automate, and for some, possibly, they may need to close.”

Fernandez warned of more kiosks, tablets and other uses of technology to take orders and check out customers in an industry that often operates on single-digit profits.

“There is a very low barrier to entry in restaurant work,” she said. “We hire young workers and people who might not have an entry to the workforce otherwise. Many of our members say they will not be able to continue to hire unskilled workers at $15 an hour.”

The D.C. measure moved ahead Wednesday after a ruling by the city’s election board, allowing proponents to begin a petition drive that is widely expected to succeed.

Several D.C. business groups opposed to the ballot measure urged the Board of Elections in briefs and testimony to reject it. The D.C. Chamber of Commerce released a poll of business owners in which more than half of the respondents said they would cut jobs if the minimum wage rose to $15.

In its ruling, the board rejected every argument by opponents.

“While the Board recognizes and can appreciate the concerns of small business owners who bemoan the prospects of increased operating costs, the Board is not authorized to reject initiatives due to financial hardships on private business owners,” the ruling stated.

Supporters must now gather about 23,200 signatures, or 5 percent of District voters, to qualify the measure for the ballot. Proponents said they are confident of clearing the signature hurdle and of prevailing at the polls. A public opinion poll commissioned in the spring by advocates showed support in the District for a $15 minimum wage at about 70 percent.

“I think it’s so popular because middle-class folks are feeling squeezed, too. Everyone understands this is an issue,” said Michael, of D.C. Working Families.

Wednesday’s developments were sure to add to the debate over the minimum wage that has already infused the 2016 presidential contest.

On Wednesday, Sen. Bernie Sanders (I-Vt.), a Democratic presidential contender, introduced a bill along with four congressional Democrats to set a national minimum wage of $15 an hour. He then addressed hundreds of striking low-wage workers outside the U.S. Capitol, calling the current federal minimum of $7.25 per hour a “starvation wage.”

Another Democratic presidential primary candidate, former Maryland governor Martin O’Malley, also recently endorsed a $15 national minimum wage, outdoing the state increase to $10.10 that he supported just last year as governor. (Virginia uses the federal minimum of $7.25.)

The overwhelming leader of the Democratic pack, Hillary Rodham Clinton, has not been precise about what figure she thinks is appropriate, either for local jurisdictions or nationally. She has given arm’s-length support to the $15 idea by dialing into a labor group forum in Detroit last month. But on a recent campaign stop in New Hampshire, she said she supports $15 an hour “in certain localities,” such as New York or Los Angeles — but not necessarily everywhere because of “different economic climates.” Clinton is expected to give a speech on wages later this summer.

On the Republican side, Wisconsin Gov. Scott Walker garnered headlines in his first weeks on the GOP presidential campaign trail by blasting the existence of any minimum wage as “lame” and serving “no purpose.”

The District’s proposed minimum wage could tee up another showdown between the city’s Democratic majority and its Republican overseers in Congress.

Although some bipartisan support exists on Capitol Hill for raising the minimum wage, a $15-per-hour rate is viewed by many conservatives as an affront to market economics. As they tried this year with the District’s marijuana legalization effort, congressional opponents could use their oversight powers to block the ballot measure from taking effect.

The D.C. measure would mirror Seattle’s by phasing in a flat $15-per-hour minimum wage by 2020. That would be 30 percent higher than the $11.50 rate that the D.C. Council and mayor, as well as adjacent counties in Maryland, agreed to last year.

Almost 43,000 District workers, or 7 percent of the city’s workforce, now earn less than $12 an hour.

As in San Francisco, the measure would also for the first time force D.C. restaurants to pay workers the minimum wage plus tips. Restaurants in the District are required to pay only $2.77 per hour, as long as tips bring servers up to the equivalent of the minimum wage.

Beginning in 2025, D.C. restaurant workers would be due $15 an hour plus tips. The minimum wage would also be indexed to inflation.

Unlike in New York, where Mayor Bill de Blasio (D) has been a forceful proponent for boosting pay, D.C. Mayor Muriel E. Bowser has remained noncommittal about supporting the $15 initiative.

As a council member in 2013, Bowser (D) voted for an increase to $11.50 an hour by 2016. At the time, that appeared likely to make the District’s minimum one of the highest in the country. But the District was quickly eclipsed.

The proposal that advanced Wednesday in New York would effectively split the state’s minimum wage into two tiers, one for those working at restaurants and the existing wage of $8.75 for everyone else. Advocates for the poor said they hoped the move would create unbearable pressure on retail and other low-wage industries to also boost pay.

The increase for fast-food workers will occur first in New York City in 2018 and then statewide in 2021.

Lydia DePillis contributed to this report.