“The Authentic Union views Sen. Sinema’s recent actions to block voting rights legislation as an affront to their company’s values, which they’re proud of and committed to upholding,” Taylor Billings, organizing director of the Campaign Workers Guild, which represents Authentic’s union, said in a statement to POLITICO.

The revolt inside Authentic underscores the degree to which Sinema has found herself in the crosshairs of her own party during the Biden years. The Arizona Democrat has rankled some of the biggest powers in Democratic circles with her refusal to back key components of the president’s agenda, most recently a reform to Senate rules to allow elections reform legislation to pass by a simple majority vote. Top women’s groups have suggested they might withdraw their support if her position remained the same. One-time donors have threatened to back a primary challenger. Even Sinema’s own digital firm has struggled with keeping her as a client.

A spokesperson for Sinema declined to comment on the situation at Authentic and instead noted that the senator supports voting rights legislation but not eliminating the filibuster to achieve it. Authentic did not return requests for comment.

Started in 2018, Authentic’s clients have included the presidential campaigns for Joe Biden and Kamala Harris. Other names touted by the firm include California Gov. Gavin Newsom, New Jersey Sen. Cory Booker, Montana Sen. Jon Tester, Boston Mayor Michelle Wu and New York Rep. Hakeem Jeffries. The firm has also done work for groups that have been stymied by Sinema’s opposition. One of them, Patients for Affordable Drugs, has advocated for the administration’s drug pricing agenda, which Sinema pushed successfully to slim down. Another client is Voto Latino, a grassroots group that recently announced a six-figure ad buy for the 2024 primary season as part of a new campaign called “¡Adios, Sinema!”

Internal union correspondences obtained by POLITICO reveal a base of workers at Authentic sparring with its management over its business with Sinema. Employees broached the topic of the firm’s contract after the senator’s vote against raising the minimum wage to $15-an-hour, during which she offered an infamous thumbs down with an accompanying curtsy, according to a person with knowledge of the discussions. Leadership at Authentic responded by making it clear that the firm did not have plans to end the contract, the person said.

A Sinema spokesperson maintained that she did, in fact, support raising the minimum wage but opposed waiving a procedural hurdle preventing it from being included in last spring’s Covid-relief bill. She was one of eight Senate Democrats to vote that way.

In mid-January of this year — as the Senate was ramping up its consideration of voting rights legislation — an Authentic employee complained once again about the firm’s contract with Sinema. “What’s the point of us supporting a client who is the antithesis of what we claim to stand for,” the employee wrote in internal correspondence, which was shared with POLITICO on the grounds that the identity of the senders would not be exposed.

“Ugh, not a good look. I feel like we have clients who would consider leaving us if they realize we work for her…” said the same employee, who also expressed fears about being passed over for a promotion if they were to say no to working on Sinema’s account. The employee also complained that the senator’s actions were effectively “letting Jim Crow 2.0 become a reality” and questioned whether the senator would reconsider if “literally no one in democratic politics wants to work with her anymore.”

“For me, the bigger question is how long until we become known as the team behind KS and it impacts all of our reputations regardless if we worked on the account,” said another member of Authentic’s staff.

Yet another employee said that “it doesn’t seem like anyone is comfortable working on her account at this point.” Employees contemplated sending a formal letter and spoke of convening over Zoom, but it was unclear whether a letter was ever sent.

Leadership at Authentic has maintained that it would not end its work on behalf of the senator. At one point, Sinema’s team offered to meet with the firm’s CEO Mike Nellis along with three employees who worked on the account to discuss the senator’s vote. The employees declined the meeting. One said the question was not about whether the Senator was aligned with their values but about how the firm responds. Another said the situation was more about where the firm stands than about the Senator.

Since the beginning of 2020, Authentic has brought in $476,776.35 from Sinema’s campaign for list acquisition along with digital and fundraising consulting. The firm was paid $44,500 in the last quarter of 2021, according to a filing with the Federal Election Commission. Authentic’s website still lists Sinema as a client.

Despite the money being spent on digital consulting, Sinema’s Senate campaign has struggled with grassroots donors. Even as her total fundraising hauls jumped year-to-year, her haul from donors that gave $200 or less in a given cycle shrunk between 2020 and 2021. Just over 2 percent of her nearly $1.6 million raised last quarter came from those grassroots donors.