(CNN) A group of former staffers to Michael Bloomberg's presidential campaign are calling on Democratic National Committee Chair Tom Perez to remove him from the slate of Democratic convention speakers, using an open letter to lambast the former New York mayor's treatment of his campaign staff.
Since Bloomberg's failed presidential campaign ended, a series of staffers have sued the billionaire politician, alleging that they were promised jobs on the campaign would be guaranteed through November. But, these staffers say, when Bloomberg's campaign ended after Super Tuesday, those promises were not fulfilled for numerous staffers and scores of people were terminated and encouraged to apply to jobs at the DNC, which had received a transfer of $18 million from the Bloomberg campaign to fund battleground efforts.
The staffers, in their letter to Perez, say that while they understand the need for a big tent Democratic Party, they "do not believe that there is a place on the convention stage for people like Mike Bloomberg who make a mockery of workers' rights -- a fundamental value that unites all Democrats."
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"This is the type of greedy, anti-worker move we'd expect from Donald Trump, but not from a Democratic presidential candidate," reads the letter, which comes from six staffers -- Alexis Sklair, Sterling Rettke, Nathaniel Brown, Brian Giles, Jocelyn Reynolds and Caryn Austen -- all of whom are party to a suit against Bloomberg over the employment matter. "The Democratic Party and its platform strongly oppose the immoral and unfair things that Mike Bloomberg did to thousands of his staffers during his presidential campaign."
The former Bloomberg aides are, instead, asking that the DNC find "another Democratic leader or workers' rights advocate" to fill Bloomberg's slot on Thursday.
Bloomberg's lawyers have noted in court that campaign aides were known as "at will" employees, meaning they could fired at any point.
And in a statement in response to the letter, a Bloomberg spokesperson notes that "like every campaign that ends, people were let go" but that after the Bloomberg campaign, the former New York mayor "gave his staff health insurance through November as well as severance."
"Although no one was promised employment through November, Mike Bloomberg remains the biggest supporter of the Democratic Party, including through a transfer of $18 million to DNC organizing efforts to hire hundreds of organizers in battleground states," the spokesperson said.
The staffers' letter also hints at lingering Democratic frustration that Bloomberg, despite the $18 million transfer, has not lived up to his promise during the campaign to spend whatever it takes to defeat President Donald Trump -- whether or not he is the nominee. The promise was usually made as a way to fight off charges that he was buying the election. Bloomberg's campaign eventually spent over $1 billion, dwarfing every other candidate in the race.
"Whether or not you can honor our request, we hope that you will ask Mike Bloomberg to make good on his promises to his staffers. It's not too late to put many of us to work to help elect Joe Biden, retain the House, and take back the Senate," the staffers write. "And it's not too late to ensure that all former field staffers receive the pay and benefits that Mike Bloomberg promised us."
A spokesperson for the Democratic National Committee did not immediately responded to questions about this story.
Bloomberg announced last week that he would be speaking at the convention, with his political organization saying in an email to supporters that the former New York mayor will explain "why we have the best candidates to meet today's challenges and get big things done." A Democratic official later said his speech would be on Thursday, the same day Biden will accept the Democratic nomination.
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"This November, America has the opportunity to turn the page on the last four years & invest in our future," Bloomberg tweeted. "That starts at the @DemConvention when we nominate @JoeBiden & @KamalaHarris. I'm honored to be speaking at the DNC next week. I hope you'll join us."
The fact that Bloomberg was included has angered liberals, many of whom believe the former Republican executive doesn't represent the party's values.
"Bloomberg does not share the best interests of the Democratic Party and he certainly doesn't share the core values of the Democratic Party," said Murshed Zaheed, a longtime progressive activist and strategist who was a vocal supporter of Warren during the primary.