WASHINGTON — Dianne Feinstein got out of her chair, grabbed a 54-page federal court opinion and poked her finger at the bullet points buried inside, insisting a visitor read each carefully as the busy senator watched and waited.
The opinion described terrorist bombing plots — aimed at New York's subways and stock exchange and at a newspaper office in Denmark — that, according to the judge, had been foiled by the government's collection of data on billions of American phone calls.
To many, the findings are in dispute. But not to Feinstein, the San Francisco Democrat who, as chairwoman of the Senate Intelligence Committee, has emerged as one of the Capitol's staunchest defenders of the nation's spy agencies.
"Let me ask you," she said. "Supposing the program is knocked out and, God forbid, a year down the pike something happens? I'd never forgive myself."
In more than 40 years in public life, Feinstein, 80, often has zigged as other Democrats zagged. In her unsuccessful run for governor in 1990, for example, she famously departed from liberal orthodoxy of the day to support the death penalty, drawing sustained boos at a state party convention.
But her crusade to preserve the National Security Agency's massive tracking programs stands out. Rarely has a senator fought so hard for something that dismays so many of her erstwhile supporters.
President Obama on Friday announced plans for the NSA to continue most of its data collection and surveillance programs, while calling for some new privacy protections. The administration is leaving it to Congress to sort out many of the details.
Feinstein praised much of Obama's speech, but expressed misgivings about a portion that would give judges more authority over some actions by intelligence analysts. The statement exemplified how Feinstein will be a key ally to intelligence officials resisting limits on their operations.
It is a rugged assignment for a California Democrat.
A nearly unanimous state Senate recently called on Congress to halt the "blanket, unreasonable, and unconstitutional collection of all Americans' telephone records."
The state Democratic Party decreed that telephone tracking efforts must stop "before they move us even further towards a totalitarian state."
Then there's the state's business community. Some of the most prominent companies in Silicon Valley, worried that customers wary of NSA snooping will take their business abroad, back legislation to unravel the NSA's collection of so-called telephone metadata, and limit its surveillance of the Internet.
After years of being routinely described as the most popular politician in the nation's most populous state, Feinstein, who is one year into her sixth term, has seen her approval rating plunge to a record low. For the first time in the more than 20 years she and the more liberal Sen. Barbara Boxer have served together, Feinstein's job approval — 43% in a Field Poll released last month — has fallen below that of the junior senator.
There is "no question" that her defense of government surveillance has driven her ratings down, the veteran senator said in a recent interview. "Numbers go down, numbers go up," she added.
"I don't think people understand it," she said of the NSA's work. "The sophisticated groups do, and they made a decision to oppose it."
On issues such as same-sex marriage, banning assault weapons and exposing harsh CIA interrogation techniques, Feinstein for years has stood shoulder-to-shoulder with many of the groups that now criticize her. Recently, she has sided with them in trying to restrict the use of drone surveillance on Americans, telling fellow senators last week about spotting a tiny drone floating outside the window of her home during a protest there. (The antiwar group Code Pink suggested she was referring to a toy helicopter it had once launched while gathered in front of the Feinstein residence.)
Even though Edward Snowden has become a hero to many of her constituents, Feinstein denounces the former NSA contractor, saying he deliberately endangered the country by releasing the spying data that caused an international uproar.
"Enormous harm has been done," she said. "This was a man who went into a company with the intention of doing this, of scraping everything he could get ahold of — and he has admitted that."
As she sees it, Feinstein has more experience with terrorism than the average American. And not just because she is chairwoman of the intelligence panel. Pressed by a reporter, she recalls, matter-of-factly, the night in the 1970s when a radical leftist group targeted her.
"They put a plastic explosive in a flower box in front of my home," she said. Luckily, it was a bitterly cold night. "This particular explosive didn't explode if the temperature dropped below freezing."
Then, the windows were shot out at the family beach house. Feinstein began packing a .38, only to give up her permit after the 1978 assassination of her colleagues George Moscone and Harvey Milk at San Francisco City Hall. She was in the building and was the first to discover Milk's body.
But she scoffs at the idea that those experiences may have colored her thinking on domestic security.
"You mean, am I paranoid? No. I am not that type," she said.
Whatever her motivation, a broad spectrum of activists on the left and right complains, saying she is a parrot for the intelligence agencies. A "Shame on Feinstein" campaign, demanding she resign from the Intelligence Committee, has been joined by tea party activists and socialists alike.
Former state Sen. Tom Hayden, a dean among leftist California Democratic activists, says the secrecy that surrounds the Intelligence Committee's activities has prevented it from effectively providing a check on the NSA.
"She is sworn to secrecy to such a level that it becomes a de facto coverup," he said. "She has been so unpersuasive. Anybody who thinks she is conducting oversight is in a very different world."
"It is very frustrating," said Mark Jaycox, legislative analyst with the Electronic Frontier Foundation. "She is supposed to take the oversight gavel, not serve as a surrogate for the intelligence community."
Feinstein is frustrated, too.
"Everything changes after an attack," she said. "Before the attack, nobody believes the work that goes into preventing it."
"I've seen some things I think you ought to know," she added. But, of course, she didn't share — the knowledge is classified.
Intelligence Committee members are typically briefed about bombing plots, terrorist cells, drone strikes and other matters in a secure room lined with lead, where phone lines are scrambled and the concrete on the floor is 8 inches thick. Officials say the elaborate security precautions are needed to protect vital secrets; critics say they help seduce panel members into sharing the worldview of the agencies they are supposed to oversee.
For whichever reason, the majority of the intelligence panel's members share Feinstein's thinking. The committee recently voted 11 to 4 in favor of a Feinstein proposal to continue the NSA's collection of telephone metadata.
of NSA surveillance activities. He said the current data collection efforts are different.
"This is all done by machines, and they don't listen to conversations," he said. "They just record where a phone call came from, where it went and if it hooked up with a third one. Virtually nothing else takes place."
But, he conceded, "we can't convince anyone of that."
In addition to battling privacy advocates, Feinstein finds herself contending with the Silicon Valley heavyweights who fear rebellion by their customers. She said she has had four conversations with Apple Inc. Chief Executive Tim Cook about the company's concerns and hopes to meet privately with several executives of major technology companies. Apple, Google, Facebook, Microsoft, Yahoo and AOL have endorsed legislation that would end the bulk collection of records.
"We have put the tech companies in an impossible bind," said Rep. Adam B. Schiff (D-Burbank), who serves on the House Intelligence Committee. "I have been hearing from them.... Their whole international business model is threatened."
The Information Technology and Innovation Foundation concluded the tech industry stood to lose as much as $35 billion in business over the next three years to foreign competitors promising more privacy. The firm Forrester Research warns of potential losses closer to $180 billion.
Schiff is among those pushing for more significant changes in the NSA's collection of phone records but, like many others in Congress battling Feinstein on the issue, won't say a negative word about her.
Colleagues like her, respect her, fear her. They also empathize. Snowden's constant disclosures have the intelligence committees on their heels.
"You get set to defend one thing, get the facts, and it is something else," Feinstein said. "It just keeps coming out.… And one day the impact will be known."