A coalition of progressive organizations published an open letter to Hillary Clinton on Wednesday, urging her to keep Wall Street veterans out of her administration if she wins the presidency.

The 15 signatories, which include advocacy groups, a labor union, a political party, and other organizations, wrote the letter to "reaffirm the importance of selecting executive branch appointees with a documented record of fighting for the public interest."

"Historically, too many Wall Street executives and corporate insiders have traveled through the revolving door between private industry and government," the letter states. "The result of this practice is that the interests of elites are over-represented in Washington."

Earlier this year, Sen. Elizabeth Warren (D-Mass.) released a report which found that Washington's revolving-door system is part of what allows corporate crime to run rampant.

The groups include advocacy organizations Public Citizen, MoveOn.org, and RootsAction.org, as well as the union Communications Workers of America (CWA), which in December endorsed Clinton's then-rival Sen. Bernie Sanders (I-Vt.) for president. Ending economic inequality became a well-known cornerstone of Sanders' campaign.

Clinton should end her controversial associations with Wall Street to demonstrate to voters that her proclaimed commitments to increasing regulation of big banks and opposing destructive trade deals like the Trans Pacific Partnership (TPP) are serious, the groups write:

We are heartened to see that the Democratic Party's 2016 platform is perhaps its most progressive one to date. But to realize its promise—including serious regulation of the banks, action to confront climate change, revitalized antitrust enforcement, support for fair trade and labor rights, progressive telecommunications policy, and so much more—we must remember the maxim, "personnel is policy." [....] As you begin to consider who would serve in your administration, we write to urge you to follow through on these commitments and the general spirit behind them. By doing so, you will ensure that your public positions on issues ranging from trade to Wall Street reform will not be undermined by executive branch appointees.

"Moreover," they continue, "we urge you to publicly state that, should you win the presidency, you will appoint personnel from backgrounds in public interest advocacy, academia, and public service to influential positions within your administration, rather than merely drawing from the usual set of corporate insiders."

The letter comes ahead of Clinton's economic speech on Thursday outside of Detroit, which progressives are using to amp up pressure on Clinton regarding her TPP stance. Though she now says she opposes the trade deal, activists are pushing for her to make her position more concrete.

Other signatories to the letter include the Center for Popular Democracy Action, CREDO Action, Daily Kos, Democracy for America, New York Communities for Change, Other98, Presente.org, Progressive Change Campaign Committee, the Rootstrikers Project at Demand Progress, and the Strong Economy for All Coalition.