Protestors descended on Amazon’s headquarters Sunday in a fight to preserve the taxing authority of Seattle and other cities in the region. The event was organized by Seattle City Council member Kshama Sawant’s “Tax Amazon” campaign.

Organizers say more than 400 demonstrators marched from Seattle’s Cal Anderson Park to the Amazon Spheres, where activists called for increasing business taxes to deal with the region’s homelessness crisis.

The protest was the latest escalation in an ongoing dispute in the Seattle area over income inequality and the role of big businesses in the region’s affordable housing crisis.

A new county-wide proposal to raise revenue for homeless services and affordable housing has become a flashpoint, sparking fear in some that the legislation would handicap cities that want to pass their own business taxes.

Washington state lawmakers are trying to pass a bill that would allow King County — home to Seattle and other cities — to implement a payroll tax on medium and large companies on the compensation they pay employees earning more than $150,000 per year. The proposal would raise an estimated $120-to-$150 million in new revenue to mitigate the homelessness crisis. The bill has support from Microsoft, Amazon, and other large employers in the area.

But privately, some in the business community are pushing for a provision of the bill that would preempt cities from passing their own payroll taxes. Preemption language hasn’t been added to the legislation but the possibility was enough to draw activists out on Sunday.

“We hope our message from this march today, and our message these last weeks has been crystal clear,” Sawant said in a statement. “If a state ban, if preemption, is added to these bills in the legislature, we will be on our way to Olympia … we will make sure there is a political price to pay for selling out the working class.”

Sawant has already proposed a higher Seattle tax that would target the top 3 percent of companies, based on their payroll expenses. She estimates her plan would raise $300 million annually for affordable public housing and environmental objectives.

Washington State Senators Rebecca Saldaña, Bob Hasegawa, and Joe Nguyen have publicly opposed adding preemption to the state bill, along with Rep. Frank Chopp.

Lawmakers’ first attempt to pass a bill authorizing King County to collect payroll taxes failed to advance beyond a cutoff deadline. The legislation’s backers introduced a replacement bill with ties to the budget, which allows it to move forward passed the initial deadline. The new legislation is similar to the initial bill, though it allows for a higher tax rate and changes the structure by which the revenue would be distributed among cities. The legislative session ends March 12.