President Donald Trump announced Saturday that he's planning to sue JPMorgan Chase (JPM) over what he calls politically motivated "debanking" after the January 6, 2021 Capitol riot. It's a legal threat that resurrects a years-old grievance and adds another layer to the already complicated relationship between Trump and America's largest banks.

In a Truth Social post, Trump accused the banking giant of "incorrectly and inappropriately DEBANKING" him after January 6. According to Trump, the account closures came at the Biden administration's urging and gave him only 20 days to move hundreds of millions of dollars to new financial institutions.

"I'll be suing JPMorgan Chase over the next two weeks for incorrectly and inappropriately DEBANKING me after the January 6th Protest, a protest that turned out to be correct for those doing the protesting," Trump wrote.

The timing is notable. This legal threat emerges just as JPMorgan has been pushing back against the Trump Justice Department's criminal investigation into Federal Reserve Chair Jerome Powell. CEO Jamie Dimon has warned that undermining the Fed's independence could send inflation expectations and interest rates higher—not exactly music to anyone's ears.

Trump also used the opportunity to address speculation about Dimon potentially joining his administration. "One was led to believe that I offered Jamie Dimon the job of Secretary of the Treasury, but that would be one that he would be very interested in. The problem is, I have Scott Bessent doing a fantastic job, A SUPERSTAR — Why would I give it to Jamie? No such offer was made there, or even thought of, either," Trump wrote.

Meanwhile, the White House is floating a proposal to cap credit card interest rates at 10% for a year. JPMorgan executives have cautioned that such a move could actually limit access to credit and hurt the very consumers it's designed to help.

For its part, JPMorgan has maintained it doesn't close accounts based on political affiliation. However, the bank hasn't denied that reputational risk considerations may have factored into decisions during that turbulent period in 2021.

If Trump follows through with the lawsuit, it could establish important precedent for how financial institutions handle politically sensitive clients going forward. The case would test the boundaries between a bank's right to manage business relationships and allegations of political discrimination—a question that's only become more relevant as "debanking" has entered the political vocabulary.