The letter, which was delivered to Senate leaders Chuck Schumer and Mitch McConnell on Friday morning, called on both parties to adopt this standard, but organizers told POLITICO it was also intended to send a message to Joe Biden’s transition team as it vets potential candidates.

“It's not addressed to Biden, but there's an understanding that he’d be in charge and be the person making nominations,” said Grijalva, an Arizona Democrat, who drafted the letter and recruited the signees.

The letter is the latest sign of the deep divisions that continue to simmer within the Democratic Party.

The clashes between the left-wing and the center — particularly over economic policy — have eased over the past several months as the factions unite to defeat President Donald Trump but are likely to reignite if Biden is victorious.

Biden would be forced to manage a potentially unwieldy coalition of aggressive left-wing Democrats and a new class of more moderate swing district Democrats from the suburbs.

Those divisions could result in an intraparty brawl over nominations for senior level posts at Treasury and other economic agencies early in Biden’s term. The dueling sides could also put Schumer in a difficult position as he tries to fend off a potential primary challenge in 2022 — possibly by Ocasio-Cortez.

The letter's signees include prominent progressive groups like Communication Workers of America, the Sen. Bernie Sanders-aligned advocacy group Our Revolution, the grassroots organization Indivisible, and the Progressive Change Campaign Committee, which is closely tied to Sen. Elizabeth Warren (D-Mass.). Many of those groups have been actively engaged in the Biden transition process, in the hopes of boosting or damaging certain executive branch appointees.

Some Biden allies and even some left-wing Democrats have been frustrated that factions of the party are airing such demands and criticism in public before the election.

The fight over personnel has its roots in the Obama administration 2008 transition, when progressives felt they had been shut out of the planning, producing an administration they believed was far too friendly to Wall Street. With a Democratic administration potentially coming in amid another economic crisis, progressives are determined to be aggressive.

“Despite the unrivaled corruption of the Trump administration, the chokehold that corporate giants and the rich hold over our political system is not new," said Illinois Rep. Jesús “Chuy” García, who also signed the letter. "Their power and influence in American politics has been growing for years."

But left-wing groups also risk overreaching. A prohibition on current and former C-suite executives is likely to draw opposition and eye rolls from more moderate Democrats, who believe private sector experience can be a valuable asset, especially given the myriad challenges currently facing the country. Biden transition officials have indicated they are prioritizing competence and values and are leveraging the former vice president’s vast rolodex for all the help they can get.

The letter's authors, however, argued that Democrats would look hypocritical if they appointed corporate-friendly officials after criticizing Trump appointees for their corporate ties.

“Just imagine explaining to the American people why those names, with those affiliations, are unacceptable, but similar names with similar-sounding affiliations are not only unobjectionable, but necessary to the proper functioning of the federal government,” they wrote. “The revolving door needs to stop, not just change direction every few years.”