• Rahm Emanuel reignited one of the longest-running debates about Obama's legacy.
• Emanuel said more Wall Street bankers should have faced justice.
• Now Biden's US ambassador to Japan, Emanuel is considering a possible run to lead the Democratic Party.

Former Obama White House chief of staff Rahm Emanuel said on Tuesday that it was a mistake that more top Wall Street executives didn't pay a price for their role in the 2008 financial crisis.

"Not only was no one held accountable, but the same bankers who engineered the crisis were aggrieved at the suggestion of diminished bonuses and government intervention," Emanuel wrote in a Washington Post op-ed. "It was a mistake not to apply Old Testament justice to the bankers during the Obama administration, as some had called for at the time."

Emanuel, Biden's US ambassador to Japan, is eyeing the potential of returning to politics by running to become the next chair of the Democratic National Committee. In his column, Emanuel said the Democratic Party has been "blind to the rising sea of disillusionment."

"When Donald Trump declared, 'I am your warrior. I am your justice. And for those who have been wronged and betrayed, I am your retribution,' he was channeling a nation's fury," Emanuel wrote. "The online cheerleading for the killer of a health-care insurance CEO in New York City is just more evidence of this seething, populist anger."

In a subtle rebuke of Vice President Kamala Harris' campaign, Emanuel said the nation is not looking for rosy optimism in a time of great instability.

"Campaigns of joy in an era of rage don't win elections," he wrote.

Emanuel's comments reignite one of the longest-running debates of the Obama era: why more top-level executives were not prosecuted in the wake of the 2008 financial crisis. Kareem Serageldin, a former top official at Credit Suisse, was the only top banker to receive a sentence connected with The Great Recession. Progressives, including Sen. Bernie Sanders, a Vermont independent, have said the lack of prosecutions is a "clear indictment of our broken criminal justice system."

Former Attorney General Eric Holder has said that the DOJ didn't have the needed evidence.

"I think you have to understand, if we could have made those cases, we certainly would have," Holder told NBC late-night host Seth Meyers in 2016. "These are the kind of things that are career-defining. People come to the Justice Department to make these kind of cases. But given the statutes we had to work with and the burdens of proof we had to meet, we were simply unable to do that."

A former mayor of Chicago, Emanuel is a polarizing figure for some in the Democratic Party. He ditched a 2018 reelection campaign for a third term amid signs that his unblemished electoral streak might be squelched. Obama's choice of Emanuel as his first chief of staff surprised some observers who saw the Illinois native as an embodiment of political insiders for a president who ran to shake up the nation's capital. He is widely regarded as a key force behind the passage of the Affordable Care Act, or Obamacare, Obama's singular domestic achievement.

Emanuel's younger brother, Ari, is a Hollywood titan and CEO of Endeavor, which owns World Wrestling Entertainment and the Ultimate Fighting Championship.

The race to lead the Democratic Party during Trump's second administration is particularly crowded. Until Emanuel formally enters the field, the three major candidates are former Maryland Gov. Martin O'Malley, Wisconsin Democratic Party chair Ben Wikler, and Ken Martin, chair of the Minnesota Democratic Farmer-Labor Party, are also in the running.

The next Democratic leader will have a high-profile role, given that Republicans will have complete control over Congress.