Striking Starbucks workers have called on supporters to delete the company's mobile app in solidarity with their ongoing fight for a first union contract.

"Starbucks customers have the power to help union Starbucks baristas win a historic first contract," Starbucks Workers United wrote on Instagram.

"Hundreds of thousands of allies have already committed to not buying Starbucks until they stop illegal union busting and finalize a fair contract – deleting the app shows Starbucks you mean it."

The demand is the latest call for solidarity since Starbucks Workers United members kicked off their open-ended Red Cup Rebellion on November 13.

Union members overwhelmingly voted to authorize the strike to start on Red Cup Day – the coffee chain's biggest sales promotion of the year in which it hands out reusable cups with certain purchases.

Since then, Workers United has filed more than 30 new unfair labor practice charges against Starbucks – including 23 charges alleging unlawful terminations and targeted retaliation.

With their #DeleteTheApp campaign, Starbucks workers are hoping to send a message to corporate leadership that they must take seriously the baristas' core demands. These include better hours to improve staffing in stores, higher take-home pay, and the resolution of charges stemming from union busting.

In a call earlier this week, AFL-CIO President Liz Shuler backed the Starbucks' workers latest campaign, saying the struggle for a fair contract is about "whether we as working people get to live with dignity in this world that we make possible."