Demonstrators rally for better wages outside a McDonald's restaurant in Chicago, Thursday, Dec. 5, 2013. Demonstrations planned in 100 cities are part of push by labor unions, worker advocacy groups and Democrats to raise the federal minimum wage of $7.25. (AP Photo/Paul Beaty)

Chicago's minimum wage workers should be earning $13 dollars an hour by 2018, according to the recommendation of the city's minimum wage task force.

The Minimum Wage Working Group, a panel created earlier this year by Mayor Rahm Emanuel, voted 13-3 on Monday in favor of a plan to gradually increase the city's minimum wage of $8.25 an hour by roughly a dollar per year until it hits $13 by 2018.

The panel's report said the wage raise would increase earnings for 31 percent of Chicago workers, according to the Sun-Times. The report also concluded the hike could increase other costs like food, health care, retail and hospitality by up to 2 percent.

The votes fell along clear dividing lines between representatives of labor and business groups: City councilmen, community leaders and labor groups voted in favor of the wage raise while representatives from the Chicagoland Chamber of Commerce, the Chicago Retail Merchants Association and the Illinois Restaurant Association voted against it, the Chicago Tribune reports.

"Increasing the largest expense on a retailer's balance sheet by 57.5 percent over four years is not sustainable or affordable," Rob Karr, president of the Chicago Retail Merchants Association, said in a released statement. "Given the many borders Chicago shares with other communities, Chicago employers will not be able to simply increase prices or they will wind up closing down as their customers seek lower prices a few short blocks away."

At least one labor group criticized the recommendation for not being high enough.

"Any recommendation that is less than $15 is an insult to the hundreds of fast food workers that have risked their jobs and made sacrifices for the well-being of this city," the Workers Organizing Committee of Chicago said in a statement.

The labor group is behind the "Fight For 15" campaign that has demonstrated dozens of times at fast food and retail outlets around the nation, including a recent protest at McDonald's suburban Chicago headquarters. According to a living wage model developed at MIT, an adult with one child in the Chicago metro area needs to make $20.86 an hour working full time just to achieve a living wage that covers basic expenses.

Illinois' minimum wage is already a dollar higher than the federal rate of $7.25 an hour, though Gov. Pat Quinn (D) supports a further state-wide increase. Residents will vote in November on a non-binding advisory measure asking if the state's minimum wage should be increased to $10 an hour.