Democrats running for president are competing to see who can sound tougher toward big business, whether their target is Wall Street or Silicon Valley.

Sen. Kamala Harris of California regularly points to how, as state attorney general, she wrestled $20 billion from the nation’s big banks in 2012 after the housing meltdown — after initially walking away from negotiations when the institutions offered $2 billion to settle. No attorney general secured more for their state from Wall Street after the mortgage crisis.

But Harris rarely mentions something else that happened in 2012: Her office declined to sue OneWest, the California bank whose CEO was now-Treasury Secretary Steven Mnuchin, an architect of the Republican tax cut law that Harris and other Democrats deride as being a giveaway to the wealthy.

Attorneys in her office had singled out the bank for allegedly stacking foreclosure proceedings against homeowners, but Harris says she was hamstrung by legal rules protecting financial institutions from state legal action.

Low-income housing advocate Paulina Gonzalez-Brito remains disappointed that Harris didn’t pursue a case.

“The question is, when push comes to shove, when you’re faced with that level of opposition from monied interests, are you willing to stand up to those monied interests?” said Gonzalez-Brito, who is the executive director of the California Reinvestment Coalition, which represents 300 community organizations, mostly in low-income neighborhoods. The nonprofit does not endorse candidates.

“In this case, Kamala Harris made a decision to not take on OneWest Bank,” said Gonzalez-Brito, who has included the hashtag #teamwarren on some of her tweets but says she has not personally endorsed Sen. Elizabeth Warren of Massachusetts or any other candidate.

“It’s unfortunate,” Gonzalez-Brito said. “It was disappointing.”

We need a leader who will unapologetically take on Wall Street. A leader who has taken on Wall Street and won. #TeamWarren https://t.co/bjHo2Ca0lS — Paulina Gonzalez-Brito (@paupau323) March 28, 2019

Some of Harris’ competitors for the Democratic nomination are ramping up their corporate-busting rhetoric and offering policy proposals.

Warren wants to break up big tech companies. She and fellow presidential candidates Sens. Amy Klobuchar of Minnesota, Cory Booker of New Jersey, Bernie Sanders of Vermont and Kirsten Gillibrand of New York asked the Federal Communications Commission to kill the proposed merger of Sprint and T-Mobile, saying it would raise prices for consumers and “harm workers.” Several candidates, including Harris, say they will not accept money from corporate political action committees.

Still, some wonder what happened in the case of OneWest.

The bank, headquartered in Pasadena, began operating in March 2009 and quickly acquired the assets of several financial institutions that had been devastated by the mortgage crisis.

As part of those deals, OneWest inherited “tens of thousands of troubled loans,” according to a 2012 memo from then-Attorney General Harris’ state Justice Department. Many of those were home loans with adjustable mortgages whose rates had spiked.

From 2009 through 2012, OneWest foreclosed on 35,000 homes in California and opened foreclosure proceedings on another 45,000, according to the memo, which was first reported by the Intercept.

The memo, written by Justice Department consumer law attorneys, said there was “evidence suggestive of widespread misconduct” in how OneWest processed loans. They said OneWest had violated state laws at least 1,000 times in mortgage foreclosures, including reducing homeowners’ chances to challenge foreclosures by backdating documents and manipulating bids at property auctions.

The memo’s authors, however, said the state investigation was “hampered by our inability to subpoena OneWest.”

“We therefore recommend that the attorney general authorize the filing of a civil enforcement against OneWest,” the lawyers wrote. If Harris approved their proposal, they said, “we will be allowed to conduct full discovery” and be in a better position to learn about other potential violations of the law.

Mnuchin was chief executive of OneWest from 2009 to August 2015, when it was sold to CIT Group. When the memo surfaced during his confirmation hearing to be Treasury secretary in 2017, his spokesman said, “Memos like this belong in the garbage, not the news.” Harris voted against his confirmation.

The California lawyers estimated that their chance of a positive outcome was “moderate,” given that the case would “be the first of its kind in California and it raises complex legal and factual issues which may lessen the prospect of settlement.” Without a settlement with OneWest, the memo’s authors said, “litigation will last 3 to 5 years.”

Ultimately, Harris did not file suit, and OneWest never paid a settlement to the state. She stands behind her decision.

“There is no question that I had very serious concerns about their conduct, and I am pretty certain based on what we knew that there should have been some accountability and consequence,” Harris told The Chronicle in an interview.

But, she said, her department’s hands were tied.

“We didn’t have the legal ability because of the way the rules were written in favor of the banks in terms of our subpoena powers as the state attorney general,” Harris said.

After she was elected to the Senate in 2016, Harris joined Warren and Democratic Sens. Dianne Feinstein of California and Richard Blumenthal of Connecticut in proposing a bill to allow state attorneys general to subpoena banks and interview their top executives. Her goal, she told The Chronicle, was “to give state AGs the power to go after federal banks and subpoena their officeholders and subpoena the people who are responsible.” It went nowhere in the GOP-controlled Senate.

Harris points to other actions she took as attorney general to help homeowners. Later in 2012, then-Gov. Jerry Brown signed a homeowners bill of rights law that Harris helped to craft. It included some of the nation’s strongest protections against practices that lenders used during the housing meltdown.

Gonzalez-Brito, the advocate for low-income California communities, praised it.

“That is an example where she was a leader and stood her ground against the monied interests,” Gonzalez-Brito said. “She was on the side of Main Street there.”

Harris also points to her creation, shortly after taking over as attorney general in 2011, of a special statewide “strike force” devoted to taking on mortgage fraud.

“The work that we did over a course of many years, including the creation of the mortgage fraud strike force, the assignment of criminal prosecutors to these cases, is the track record of my work on this issue,” Harris said. “If we could have gone after OneWest, we would have.”

The unit’s work continues, “though we no longer refer to those working on these matters as the mortgage fraud strike force,” said Tara Gallegos, spokeswoman for California’s current attorney general, Xavier Becerra.

She said the unit works on “prosecutions of individual loan modification scams of varying size and complexity” and “broader cases” involving banks.

Since the creation of the unit in 2011, Gallegos said, the state Justice Department has “prosecuted 41 mortgage fraud cases.”

As a presidential candidate, Harris has proposed policies intended to close a wealth gap that progressives argue was worsened by the mortgage meltdown. Among them are a plan to give a $6,000 annual tax credit to families earning less than $100,000 and a proposal to raise teachers’ salaries with increased inheritance taxes.

Joe Garofoli is The San Francisco Chronicle’s senior political writer. Email: jgarofoli@sfchronicle.com Twitter: @joegarofoli. Tal Kopan is The San Francisco Chronicle’s Washington correspondent. Email: tal.kopan@sfchronicle.com. Twitter: @TalKopan