The Portland Green Independent Committee says a majority of city residents support increasing the minimum wage to $15 an hour.

The Portland Greens are currently collecting signatures for a November referendum that would require all Portland businesses to pay their employees at least $15 an hour – what the group calls a livable wage – by 2019. Businesses with 500 or more employees would have to comply by 2017.

The Greens commissioned a poll by the Raleigh, North Carolina-based Public Policy Polling, which surveyed 507 residents from April 19-21. The poll has margin of error of +/- 4.3 percent.

The PPP poll showed that 55 percent of survey respondents favored a $15 an hour wage, according to the Greens. The proposal was most popular with Democrats (70 percent), followed by women (64 percent), seniors (60 percent) and young voters (56 percent).

“We believe that this poll indicates that Portland residents strongly believe that working full time should be a ticket out of poverty for working families,” Chairman Tom MacMillan said in a written statement.

Polls conducted by private parties are considered less reliable than public polling because sponsors tend to release results only when they favor their interests.

The Greens have until June 19 to collect at least 1,500 valid signatures from registered Portland voters to put the referendum on the November ballot.