Mayor Ed Murray put on another display of political muscle on Thursday, garnering eight of nine Seattle City Council members as co-sponsors of his proposal for a three- to seven-year phase-in of a $15-an-hour minimum wage in the Emerald City.

The wage resolution runs to 18 pages. It contains 10 “whereas” clauses, 11 “findings of fact and declarations,” 23 definitions of terms, and one quote from President Obama — who took three-quarters of Seattle’s vote — that income inequality is “the defining issue of our time.”

The odd-member out is socialist Seattle City Council member Kashama Sawant, who did not sign on as a cosponsor and was one of three members of Murray’s 24-member Income Inequality Advisory Board not to sign on to the proposal.

Sawant was in the streets Thursday, joining a noisy strike by fast-food workers that swept from franchise to franchise, starting Wednesday night with the McDonald’s on First Hill.

She joined demonstrators in front of a downtown McDonald’s and, reported Publicola, signed a Seattle Charter initiative petition that would impose a $15 minimum wage a lot quicker than Murray’s proposal.

It is not clear whether the left-activist group 15 Now, heavily influenced by Sawant’s Socialist Alternative movement, will want to put the measure on the fall ballot. Organized labor has lined up behind the Murray proposal.

An EMC poll, released earlier this week, found 57 percent voter support for a plan like Murray’s, but only 41 percent backing a steeper, quicker imposition of a $15 minimum wage.

The City Council can pass Murray’s plan into law, a prospect enhanced by its having eight sponsors. The council will take up the mayor’s plan at midday on May 22.

The United States may still be a moderately conservative country, but Seattle is proud to be a beacon of progressive activism.

It has been that way since a Seattle general strike nearly 100 years ago, through FDR Postmaster General James Farley’s 1930s description of “47 states and the Soviet republic of Washington,” and through mass protests against the Vietnam and Iraq wars.

Slogans used by Thursday’s fast-food strikers were first chanted in anti-war and anti-racism marches down Pine Street nearly 50 years ago.

The 18-page minimum-wage resolution rings with talk of soaring wages for the very rich, economic stagnation for the average worker, and the need to “promote the general welfare, health and prosperity of Seattle.”

It notes that an estimated 100,000 people or more who work in the city earn wages insufficient to live in the city. It notes that a majority are women and people of color, and that 13.6 percent of Emerald City residents live below the poverty line.

A bit grandly, it celebrates Seattlites who “struggle to meet their basic needs,” bemoans “the increasing unaffordability of this city for so many of our citizens,” and denounces “the hollowing out of the middle class.”

As a state legislator, Murray worked 17 years to pass LGBT civil rights legislation, an anti-bullying bill, civil unions legislation and, finally, marriage equality. He could get hot under the collar but displayed the patience of Job.

He has taken a similar approach to the $15-an-hour wage issue. A panel was co-chaired by SEIU union leader David Rolf and business leader Howard S. Wright III. The mayor held out for what he called a “super majority” of the committee, and got it.

The plan would give large businesses, those employing more than 500 people, three years to ramp up to a $15-an-hour minimum wage. The state’s minimum wage is currently $9.32 an hour. Benefits such as tips would initially be included in factoring the wage.

Small businesses, particularly family restaurants, would get longer, up to seven years in some cases.

Once the $15 minimum is reached, the wage would rise each year at the rate of inflation.