Democratic 2020 U.S. presidential candidate and U.S. Senator Bernie Sanders (I-VT) greets supporters before marching in the Nashua Pride Parade in Nashua, New Hampshire, June 29, 2019.

After a prolonged dispute between Sen. Bernie Sanders and the union representing his presidential campaign staffers, the two parties reached an agreement that will pay field organizers the equivalent of at least $15 an hour.

A $15 minimum wage, and workers' rights more broadly, are centerpieces of Sanders' platform. But field organizers were being paid an average of less than $13 an hour, according to internal communications leaked to The Washington Post.

In a CNN interview Tuesday morning, Sanders announced that the campaign reached a deal with the union that would pay field organizers an annual salary equivalent to $15 an hour. The agreement followed a union dispute that had dragged on since at least May, according to the Post.

"Both the campaign staff and management have engaged in this process in good faith and to achieve a mutually agreed upon outcome. This is what democracy in the workplace looks like," said Jonathan Williams, a spokesman for the union, United Food and Commercial Workers Local 400.

He noted that the campaign will pay its field organizers $42,000 per year for up to 50 hours a week, which works out to more than $15 per hour.

Sanders said he was happy the union accepted his campaign's offer.

"I respect workers rights and I respect the union movement," he told CNN. "I'm proud that all of our workers are going to be well paid."

Sanders Video

His campaign elaborated in a statement.

"We have and will always be committed to the fight for fair pay, decent work conditions, and a strong labor movement-- for our own workers and those all across this country," campaign manager Faiz Shakir said in the statement. "We're proud to have successfully negotiated with the union in good faith to raise the pay of field organizers, while continuing to ensure our campaign staffers are being paid a living wage."

No hours or positions are being cut to accommodate the salary increase, according to Williams.

Sanders' campaign was the first presidential campaign to unionize. Several others have since followed suit, including Sen. Elizabeth Warren's and former Housing and Urban Development Secretary Julian Castro's campaigns.

Rep. Eric Swalwell's campaign had unionized, but Swalwell dropped out of the race in early July.

— CNBC's Sunny Kim contributed to this report.