Supporters of a tax increase on big retailers' Portland sales to pay for eco-friendly causes have gathered more than enough valid signatures to appear on the ballot this fall, the city election office announced.

If adopted, the Portland Clean Energy Community Benefits Initiative, officially called PDX 04, would levy a 1 percent tax on all Portland sales by businesses with at least $1 billion in annual revenue and $500,000 in sales within city limits. Groceries and medicine would be exempt from the tax.

Backers say the tax would raise at least $30 million a year. Money would be set aside in a fund for clean energy projects and eco-jobs training for women, people of color, the disabled and "chronically underemployed."

Public opinion about PDX 04 is unclear because no polling data has been released, but Portland voters are typically a tax-friendly electorate. Multnomah County was one of only two counties to vote yes on Measure 97, the statewide retailer tax that appeared on 2016 ballots.

Backers of the tax include more than 100 grassroots political organizations, nonprofits, members of clergy and Commissioner Chloe Eudaly. Mayor Ted Wheeler has come out against the tax, as have the Portland Business Alliance and the Oregon Business Council, an advocacy group for the state's largest employers.

-- Gordon R. Friedman