Backers of the Portland Clean Energy Fund measure on the November ballot have added a marquee name to their endorsement list—U.S. Sen. Jeff Merkley.

Merkley, who has carved out a reputation as one of the loudest progressive voices in the U.S. Senate and is said to be contemplating a run for president, joins a long list of environmental groups and left-leaning politicians in the effort to levy a 1 percent surcharge on the business income tax paid by retailers with revenues of more than $500,000 in Portland and more than $1 billion nationally.

The money raised—estimated to be $30 million a year—would be used for weatherization projects and job training for low income and minority workers.

Opponents of the measure—known as 26-201—have disclosed accounts payable (i.e. expenditures) of $178,000 so far, while proponents have not yet disclosed any contributions since qualifying for the November ballot. They spent about $205,000 to qualify.