Former President Obama's upcoming speech to Wall Streeters is putting $400,000 in his pocket - and putting longtime supporters in a difficult situation.

Democratic Party leaders and grass roots activists alike are at a loss to explain how the onetime champion of the 99 percent could cash in with a September address at a health care conference run by investment firm Cantor Fitzgerald.

“Spiritual leader of the people’s #Resistance cashes in with $400k speech to Wall Street bankers,” read one tweet.

"[Money] is a snake that slithers through Washington.” — Sen. Elizabeth Warren, D-Mass.

“Obama’s $400,000 Wall Street speech will cost @TheDemocrats much more than that," read another. "It reinforces everything progressives hate about Democrats.”

Sen. Elizabeth Warren, D-Mass., said she “was troubled by that,” when asked her opinion on Sirius XM’s “Alter Family Politics” radio show this morning. But she held back from criticizing the president directly while referring repeatedly to her new book, “This Fight is Our Fight,” in which she outlines her concerns about big money’s influence on American politics.

“One of the things I talk about in the book is the influence of money. It’s a snake that slithers through Washington,” Warren said.

Calls to other prominent liberal elected officials, including Sen Bernie Sanders, the Vermont Independent who ran hard for the Democratic presidential nomination by championing the middle class and denouncing Wall Street, and Senate Minority Leader Chuck Schumer were not immediately returned.

@thehill As well he should. He served us faithfully and well for 8 years as President - he doesn't work for us anymore. More power to him. — (((Morgan Harris))) (@mharris621) April 25, 2017

While Obama's longtime allies in Washington were taciturn, far-left groups that viewed him as their champion could not hide their bitterness.

"Even if he donates the money from this Wall Street firm to charity, his speech and remuneration reminds 'ordinary' working class people that both major political parties are in bed with Big Business," said David Michael Smith, of the Houston Socialist Movement. "In my view, our country needs a new kind of political party and social movement to represent the vast majority of the population, not the wealthy few."

The fee - equal to one year's presidential salary - was not the issue with critics so much as the idea a leader the Democratic base always considered beyond the reach of Wall Street taking it.

“Now Democrats are being put in the position of deciding whether their former president should take $400,000 from Wall Street for a speech," the left-leaning Washington Post wrote. "At the least, it risks suggesting the party's anti-Wall Street posture is in some cases just that — posturing.”

Some of Obama's supporters saw nothing wrong with the former president's pay day.

"He served us faithfully and well for 8 years as President - he doesn't work for us anymore. More power to him," one supporter wrote on Twitter.

Obama spokesman Ed Schulz insisted the former president remains true to his progressive values, and said taking money from Wall Street is not the same as being bought by Wall Street.

“With regard to this or any speech involving Wall Street sponsors, I'd just point out that in 2008, Barack Obama raised more money from Wall Street than any candidate in history — and still went on to successfully pass and implement the toughest reforms on Wall Street since FDR,” Schulz said.

Still, the development seemed a far cry from sentiments Obama expressed in his 2006 memoir, “The Audacity of Hope.”

“The path of least resistance - of fund-raisers organized by the special interests, the corporate PACs, and the top lobbying shops - starts to look awfully tempting, and if the opinions of these insiders don’t quite jibe with those you once held, you learn to rationalize the changes as a matter of realism, of compromise, of learning the ropes,” then-Sen. Obama wrote. “The problems of ordinary people, the voices of the Rust Belt town or the dwindling heartland, become a distant echo rather than a palpable reality, abstractions to be managed rather than battles to be fought.”

Obama will have an opportunity to reconcile his evolving position on money and politics in his next memoir, for which he has already signed a $60 million deal.