Jeffrey MacMillan/For Washington Post/getty

The scandal-plagued U.S. bank Wells Fargo & Co. (WFC - Get Report) is "too big to manage," a top U.S. lawmaker told CEO Tim Sloan at a hearing Tuesday in Washington.

Maxine Waters, a Democratic congresswoman who heads the U.S. House of Representatives' Financial Services Committee, said at the hearing that Wells Fargo is blighted by "ongoing lawlessness and failure to right the ship." Waters represents a district in southern California, where some of the San Francisco-based bank's alleged customer abuses first emerged. 

It was the first time Sloan has appeared before the House panel since Democrats took control of the chamber following last November's elections. He has previously appeared before the Senate Banking Committee, where he was harangued by Sen. Elizabeth Warren, a Massachusetts Democrat who is seeking the Democratic nomination for president. Warren has repeatedly called for Sloan's dismissal. 

A series of alleged cases since 2016 involving customer mistreatment have now cost the bank more than $4.5 billion in settlements and forgone revenue. The bank's executives acknowledged that employees opened more than 3 million unauthorized accounts in the names of customers.  

Sloan, who has worked at the San Francisco-based bank for three decades, was appointed to run the bank after former CEO John Stumpf stepped down under pressure in 2016.

A year ago, the Federal Reserve ordered Wells Fargo to refrain from further asset growth until it overhauled risk management and corporate oversight. The bank has since replaced several directors who failed to prevent the improper sales practices.

Sloan announced in January that the Federal Reserve sanctions would likely remain in place at least through the rest of 2019; initially, executives had predicted they could wrap up the case by the end of last year. 

Yet Sloan has endured, despite a series of tweets from Warren in January in which she said his "hands are too dirty from overseeing years of scams and scandals."

In prepared remarks submitted to the House panel ahead of Tuesday's hearing, Sloan said Wells Fargo has undergone a "transformation" under his leadership and "gone above and beyond what is required in disclosing these issues in our public filings." 

"We have worked to remedy these issues and, most importantly, we have worked to address root causes that allowed them to occur in the first place," Sloan said in the prepared remarks, which were posted on the bank's website.  

But it wasn't just Democrats lashing into Sloan at Tuesday's hearing. 

Patrick McHenry, the top Republican on the panel, said Wells Fargo repeatedly has promised to fix its flaws but "a few months later, we hear about another case of dishonest sales practices or gross mismanagement." 

Sloan told McHenry that he had worked hard to address the issues and improve the company's corporate culture, and that there were no other major scandals brewing that haven't been disclosed. Sloan added, however, "I can't promise you perfection."