WASHINGTON — Chants rang out as more than two hundred disgruntled postal workers rallied in downtown Washington against Staples stores Thursday, forcing anyone who wanted to grab office supplies to cross a picket line.

The group, a mix of current and retired postal service employees as well as members of the American Postal Workers Union, marched from Farragut Square to the Staples several blocks away. Holding bright blue picket signs and wearing matching T-shirts, they chanted “Whose post office? The people’s post office!” and “U.S. mail is not for sale.”

They’re protesting the unionized postal workers’ jobs they say are going to lower-paid Staples workers, thanks to mini-post offices that were set up inside the office supply chain stores as a pilot program last November. Staples employees will staff the quick-service counters.

Mark Dimondstein, president of the American Postal Workers Union, called it a “dirty deal,” noting that the average postal worker earns just under $25 an hour while the average Staples worker earns about $9 an hour.

“We can talk all we want about income inequality, but when you take good union jobs and shift them into the private sector, that’s doing the opposite,” Dimondstein said.

The Postal Service ended the first quarter of 2014 with a loss of $354 million. It’s the 19th of 21 quarters marked by a loss and blamed on the lack of postal reform legislation combined with a decline in First Class mail.

As for the expanded service hours the post office locations inside the Staples stores offer, Dimondstein said they’re not asking for the postal units to be shut down.

“We ask that they be staffed with postal employees so people can still have that access but have it done by trusted and trained employees,” he said.

Gloria Hinton spent 35 years working for the United States Postal Service. With a picket sign in hand, she said postal workers take an oath when they get the job, which she believes makes all the difference.

“Do you want to trust your mail to someone that could be gone next week?” Hinton asked.

Staples spokesman Mark Cautela said the company doesn’t provide details on pilot programs or agreements with vendors, but added that they “continually test new products and services to better meet the needs of our customers.”

In a statement, the postal service management defended the partnership and said it’s a way to “grow the business.”

“Because the Postal Service receives no tax dollars for operating expenses, and relies on the sale of postage, products and services to fund its operations, this retail partnership program could be an innovative step towards generating revenue to ensure the long-term viability of the Postal Service,” the statement said.

The protest, part of the union’s National Day of Action, occurred at 50 Staples stores in 27 states, and Washington, D.C.