As many as 3.5 million accounts were involved as employees tried to meet aggressive cross-selling goals that have since been scrapped.

"What in God's name were you thinking?" asked Republican Sen. John Kennedy of Louisiana.

Other members of the committee also pressed Sloan about how the bank could have allowed the sales scandal to get so out of control.

"At best you were incompetent, at worst you were complicit," the Massachusetts Democrat said during Sloan's appearance before the Senate Banking Committee. "Either way, you should be fired."

Sen. Elizabeth Warren on Tuesday demanded that Wells Fargo CEO Timothy Sloan be fired, arguing that he was part of a culture that pushed the bank to create millions of fake accounts for customers without their knowledge.

Wells Fargo Chief Executive Officer and President Timothy Sloan testifies before the Senate Committee on Banking, Housing and Urban Affairs on Capitol Hill in Washington, Tuesday, Oct. 3, 2017, during a hearing on Wells Fargo after one year.

Though Sloan said he believes the bank was making strides in restoring its reputation, Warren and others weren't impressed.

"Wells Fargo needs to start over, and that won't happen until the bank rids itself of people like you who led it into this crisis," said Warren, who previously had demanded that the 12 board members in place during the scandal be removed.

Warren pushed Sloan on comments and transcripts she found in news articles and earnings calls that she said showed the CEO was bragging about the bank's sales ability even as he knew about the cross-selling problems.

"I've read through them, and on these calls no one, not even John Stumpf, who was the CEO at the time, bragged more about Wells Fargo's ability and commitment to open new accounts for existing customers," Warren said, referring to earnings calls between 2011 and 2014.

"I'm proud of the credit card products we have at Wells Fargo," Sloan responded.

Sloan defended his role at the bank, sidestepping questions over why he hadn't acted sooner and instead focusing on the steps he was taking now. Sloan was chief operating officer before succeeding Stumpf, who was forced out as CEO last October, a month after the bank settled charged with regulators over the cross-selling practice.

Sloan outlined a number of steps Wells Fargo is taking to improve operations and prevent a similar scandal.

" I don't believe your criticisms of the board are accurate," he later said. "I think the reason I am the right person to run this company today, notwithstanding your criticisms, is because I have been making change at this company for 30 years."

"I'm not afraid to make hard decisions when it's needed, and I have the support of 270,000 people," he said, referring to the bank's employees. "That's why I think I'm the right person."

"Are you kidding?" Warren responded.

Their exchange continued later, with Warren charging that Wells Fargo was planning to lay off thousands of employees to meet shareholder profit expectations.

Addressing committee chair Sen. Michael Crapo (R-Idaho) on the broader issue with the banks, she said, "The only way we're ever going to stop these scandals is to hold executives personally accountable, to fire the people who are responsible and when they break the law to march them out in handcuffs."

"I couldn't disagree more with almost everything Sen. Warren said," Sloan responded.

Warren also went after Sloan's predecessor at a hearing last year. She called for a criminal investigation into Wells Fargo executives and told Stumpf he should resign.