WASHINGTON — As crowds converged on airports around the country to protest President Donald Trump’s first travel ban, the phone rang at the home of Homeland Security Secretary John Kelly.

It was a Saturday night in late January, and Kamala Harris, California’s new senator, was on the line. She had been getting frenzied texts from lawyers at SFO and LAX whose clients were blocked from entering the country, even after a judge had stayed the ban — and she wanted Kelly to do something about it.

“Why are you calling me at home?” asked Kelly, a retired four-star general, Harris later recounted. “I said: ‘Because these families are there and there’s a stay that just got issued. So you need to let them go.’”

That bluntness has helped Harris — California’s first new U.S. senator since 1992 — stake out a position as one of the leaders of “The California Resistance,” raising early speculation about her presidential aspirations. With a bold progressive streak, the politician once known for playing it safe is showing in her first months in office that she’s not afraid to break a few conventions of the typically stodgy Senate.

“There’s so much at stake right now,” she said in a recent interview in her Senate office. “This is not just Plato and Socrates debating the issues of the day. … It’s about policies and an administration that is making decisions every day that impact the lives of real human beings.”

Harris rallied Trump opponents in Washington at the Women’s March in late January and joined protests outside the White House. She voted against 18 of Trump’s top nominees — more no votes than all but five other senators. And she’s putting her newfound bully pulpit to use, haranguing Trump and his administration in a series of high-profile speeches.

In short, the 52-year-old Harris is throwing out the playbook followed by other first-term senators who come to the Capitol with political star power. Senators like Barack Obama, Hillary Clinton and Al Franken spent their early years in Washington keeping their heads down and shying away from attention — but not Harris.

During the interview, Harris, a former prosecutor and state attorney general, launched into a list of Trump’s goals: gutting the Affordable Care Act, defunding Planned Parenthood, denying climate change, restarting the war on drugs — her voice rising until she realized she was working herself up.

“I didn’t mean this to turn into a speech,” she said, cracking up and leaning back into her office couch. “Write this down!”

This to-the-barricades posture seems to come naturally to Harris — and it’s in perfect tune for a bright blue state whose residents are generally disgusted with the president.

“Trump’s election has given her the opportunity to elevate herself from being just another freshman senator,” said Jack Citrin, a political science professor at UC Berkeley. “For California in particular, Trump is a great piñata.”

In Washington, Harris has focused on a few big issues, especially immigration. Her first bill, the Access to Counsel Act, would force immigration officials to let attorneys reach people stuck in limbo at U.S. ports of entry. Her staff helped refugees affected by the travel ban connect with their families.

Other legislation she’s co-sponsored would shield undocumented farmworkers from deportation. She’s also pushed the Trump administration to honor the waiver letting California enforce tough vehicle emission standards — and successfully fought for disaster funding after California flooding earlier this year.

At Senate hearings, Harris has grilled Trump appointees. The no-nonsense questioning often resembles a cross-examination, with little of the congenial chitchat that peppers many senators’ questions.

She’s also working on the Trump-Russia investigation as a member of the Senate Intelligence Committee. On the prospect of impeaching Trump, she said, “Is there a potential for it? Apparently yes, but that’s not something I’m going to call on at this point.”

But Harris’ focus on Trump rubs some of her Republican constituents the wrong way. “She’s spending a lot of time criticizing President Trump,” said Sue Caro of Oakland, the California Republican Party’s vice chairwoman for the Bay Area.

“In California, we have rising poverty, failing schools, crumbling infrastructure — and all she wants to talk about is Trump, Trump, Trump,” Caro said.

Harris, the child of immigrants from India and Jamaica, is the first Indian-American and second female African-American senator in U.S. history. She has also hired a team that’s far more diverse than in most congressional offices: Two-thirds of her staffers are people of color, and more than half are women.

The new senator was born in Oakland and grew up in Berkeley. Her parents met as graduate students at UC Berkeley and divorced when she was a young child, and she was raised mostly by her mother Shyamala, a physician. Her dad was an economics professor at Stanford.

Harris went to Howard University, a historically black college in Washington, D.C., where she ran her first political campaign, winning a race for freshman class representative. She also interned for California Sen. Alan Cranston, who occupied the same Senate seat she holds today.

She got her law degree at UC Hastings and worked as a prosecutor in Alameda County and San Francisco, trying murder and other felony cases. She won a bruising race for San Francisco district attorney in 2003, defeating Terence Hallinan, her old boss, and went on to be elected state attorney general in 2010.

In California political circles, Harris had gained a reputation for tiptoeing around contentious issues — in part because of her former job as the state’s top law-enforcement official. One exception: her 2004 decision as San Francisco DA not to bring the death penalty against a man accused of fatally shooting a police officer, which earned her the ire of police unions and most of the state’s elected officials.

Those who’ve followed her political career say Harris has let loose since arriving in Washington. Last month, during a live recording of the Pod Save America podcast in San Francisco, she even dropped a couple of F-bombs: “What the f— is that?” Harris wondered aloud about a Republican congressman’s statement that people don’t die because they don’t have health insurance.

Former Sen. Barbara Boxer, who Harris replaced, said in an interview that she thought Harris was continuing her progressive legacy. “I’m very pleased that we have a real fighter in my seat,” Boxer said. “Usually, when you first come in, you’re learning the ropes and taking care of business for your people. She’s got to do that and be a voice of conscience against the Trump administration.”

If Clinton had defeated Trump in 2016, Harris said, she’d be playing a different role as senator. During her campaign against former Rep. Loretta Sanchez, an Orange County Democrat, Harris talked about passing comprehensive immigration reform, overhauling the criminal justice system, and making community college free.

But those possibilities all but evaporated on election night. When Harris came onstage at a downtown L.A. nightclub to give her victory speech, it was becoming clear that Trump was headed to the White House. She only briefly mentioned her own race before addressing the national election. “Do we retreat or do we fight?” she asked. “I say we fight.” She repeated the word fight 33 times in eight minutes.

“If Washington were a Hollywood movie, you couldn’t cast anyone more different than Donald Trump” — an eloquent, deliberate, relatively young, mixed-race daughter of immigrants, said Nathan Ballard, a San Francisco political consultant who served as deputy city attorney alongside Harris in the ’90s. “She’s right at home in the resistance.”

Her high-profile role has also fanned rumors about her political future. Some supporters want her to follow Obama’s playbook and jump into the 2020 presidential race midway through her first term as senator.

But some political analysts say exercising a bit of her previous cautiousness might help her in the long run.

While there’s little electoral downside in California to Harris’ strident criticism of Trump, her fiery rhetoric, to say nothing of the F-bombs, might not play as well across middle America if she does decide to run for president someday, said Bill Whalen, a former GOP strategist who is now a research fellow at Stanford’s Hoover Institution.

Harris said she finds all the speculation “distracting.”

“Listen, 2020 is in how many years? We are in the Year of our Lord 2017,” she said. “There is so much happening in real time right now. I’ve seen so many people focus on the thing that’s far out there — and trip over the thing that’s in front of them.”

Kamala Devi Harris

Job: U.S senator

Education: Howard University and UC Hastings Law School.

Experience: Former California attorney general and San Francisco district attorney. Worked as Alameda County prosecutor.

Quote: “There’s so much at stake right now. This is not just Plato and Socrates debating the issues of the day. … It’s about policies and an administration that is making decisions every day that impact the lives of real human beings.”

Fun fact: Interned for California Sen. Alan Cranston, who held the same Senate seat.