WASHINGTON — When Equifax CEO Richard Smith testifies in front of two congressional committees during the first week of October, it won’t just be his job at stake.

If Smith performs poorly before the House Energy and Senate Banking panels, it will not only bolster calls for him to be fired over the data breach that saw 143 million consumer records become compromised, but will also add significant momentum to a push to reform the credit bureaus.

“Lawmakers have no real idea for how to address the worries of their constituents,” Jaret Seiberg, an analyst for Cowen and Co., wrote in a note to clients. “That is why we see risk for Equifax and the credit bureaus from this breach. There is the possibility that it forces Congress to act without full consideration of the ramifications of a legislative solution.”

Fortunately for Smith, he has a guidebook of sorts provided by Wells Fargo — of precisely what not to do when testifying before Congress. Roughly a year ago, then-Wells CEO John Stumpf testified before two congressional panels on the bank’s phony-accounts scandal. In the aftermath of that hearing, he was forced to resign, there were more calls to break up the megabanks and Wells struggled to escape the shadow of its wrongdoing.

Then-Wells Fargo CEO John Stumpf appeared unprepared and ready to shift the blame to low-level staff during two hearings last year on the bank's phony-accounts scandal. He later resigned. Bloomberg News

Following is a guide to how Equifax and Smith can learn from Wells’ mistakes. These same principles can also be followed by Stumpf’s successor, Wells CEO Tim Sloan, who will also testify before Congress next week to defend his company’s practices a year after the bank’s scandal.

Be careful whom you blame

It’s difficult to overstate how poorly Stumpf performed when he appeared before the Senate Banking Committee on Sept. 20, 2016. Arguably his biggest mistake was his apparent attempt to minimize the scandal and put the blame squarely on roughly 3,500 former low-level employees who opened as many as 3.5 million phony accounts.

Stumpf repeatedly noted that that number only represented roughly 1% of Wells’ workforce. But lawmakers saw this as an attempt to shift responsibility from the bank’s senior management and board of directors.

“Every time you say that, you give ammunition to the folks that want to break up the big banks," Sen. Jon Tester, D-Mont., said during the hearing. "This is a major screw-up that went on for far, far too long. I think you know that.”

Smith will testify before the House Energy Committee on Oct. 3. and the Senate Banking panel a day later. While it’s unclear how he will explain a breach as large as that which hit Equifax, he would do well to avoid looking like he is avoiding responsibility for a disaster that happened on his watch.

Come prepared

Blaming lower-level staff wasn’t Stumpf’s only unforced error, however. He frequently appeared unprepared for lawmakers’ questions, including about the extent of Wells’ wrongdoing, when he became aware of the fraud and whether the matter should have been disclosed in public regulatory filings.

Stumpf’s most prevalent answer was a version of this: “I don't know the numbers, I have to talk to our team."

At other times, he gave seemingly contradictory statements, for example when he tried to maintain that senior managers like Carrie Tolstedt, previously the head of Wells’ community bank department, had been held to account, while also saying that she’d voluntarily chosen to retire.

What’s worse is that Stumpf didn’t appear to learn much from his first disastrous appearance on Capitol Hill. After being widely lambasted during his testimony before the Senate Banking Committee — even Wells employees were privately stunned at how badly it had gone — Stumpf was not much better two weeks later when he appeared before the House Financial Services Committee on Sept. 29, 2016.

Stumpf spent part of that hearing paging through a binder trying to find information on how many customers had been impacted in each state, but still couldn’t answer critical questions about how many employees were fired, what Wells did about the internal complaints it received and what senior management did when they learned of the fraud. Lawmakers from both parties were stunned.

"I'm amazed at what you do not know about your business," said Rep. Roger Williams, R-Texas. "I'm amazed at how many 'I do not knows' I've heard."

Stumpf’s seeming lack of knowledge was so bad that Rep. Maxine Waters, D-Calif., announced she was drafting a bill to break up the bank.

“I am committed to breaking up Wells Fargo and if that leads us to a conclusion that all the big banks should be broken up — they are too big to manage," Waters said.

If Smith wants to keep his job — and protect his industry — he had better show up with better answers than, “I don’t know.”

Anticipate hard questions from Elizabeth Warren

To some extent, the media can sometimes put too much emphasis on a single lawmaker like Sen. Elizabeth Warren, D-Mass. Though popular in progressive circles and a possible Democratic presidential candidate in 2020, she remains a single senator in a body of 100.

During the Stumpf hearing, for instance, several senators from both parties asked tough questions and took the CEO to task for the bank’s failures.

That said there’s little doubt that Warren is a potent interrogator for at least two reasons. One, she seems to have a prosecutor’s knack for sizing up her opponents and cutting straight through their arguments. For the unprepared or insecure, her cross-examinations can be brutal, as it was for Stumpf. Warren was one of the first to tell him he should resign, but other lawmakers followed her lead.

Secondly, Warren’s many progressive fans are adept at amplifying Warren’s message, giving it more influence than it might otherwise have.

This is unfortunate for Equifax’s Smith, as Warren has already made clear she’s gunning for him.

“So long as there is no personal responsibility when these big companies breach consumers' trust, let their data get stolen, cheat their consumers, like they did in the case of Wells Fargo, then nothing is going to change,” Warren told CNBC’s Jim Cramer last week in an interview.

Moreover, Warren has taken the lead in trying to reform the credit bureaus. She co-authored along with Sen. Brian Schatz, D-Hawaii, a bill that would create a federal requirement for credit bureaus to offer free credit freezes to consumers affected by a data breach. Many analysts see the bill as measured and capable of picking up bipartisan support.

At the very least, Smith will have to be well prepared for his questioning by Warren, who will be using her time to advance her legislation and show Equifax’s mistakes. But some argue he should do one better — and give Warren what she wants.

“We believe the best strategy may be for Smith to announce that in an era of increasingly sophisticated hacking that Equifax will offer free credit monitoring and free credit freezes to all consumers,” Seiberg wrote of Cowen. “Our view is that Equifax is going to be forced to do this anyway either in response to state litigation or federal legislation. So it is better to get credit for it upfront. This can help shift the debate and paint Equifax as part of the solution rather than the problem.”