WASHINGTON (AP) — President Joe Biden had a question.

“Is it true?” Biden asked Sen. Alex Padilla, referencing the roughly 25% of U.S. students in kindergarten through high school who are Latino. Padilla said the question came as he was waiting with the president in a back room at a library in Culver City, California, before an event in February.

It was exactly the kind of opening Padilla was hoping to get with the Democratic president. Biden was weighing his reelection campaign, executive actions on immigration and what to do about a southern border that has been marked by historic numbers of illegal crossings during his tenure.

Padilla wanted to make sure Biden also took into account the potential of the country’s immigrants. “Mr. President, do you know what I call them, those students?” Padilla recalled saying. “It’s the workforce of tomorrow.”

It was just one of the many times Padilla, who at 52 years old is now the senior senator of California, has taken the opportunity — from face-to-face moments with the president to regular calls with top White House staff and sometimes outspoken criticism — to put his stamp on the Democratic Party’s approach to immigration.

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The son of Mexican immigrants and first Latino to represent his state in the Senate, Padilla has emerged as a persistent force at a time when Democrats are increasingly focused on border security and the country’s posture toward immigrants is uncertain.

Illegal immigration is seen as a growing political crisis for Democrats after authorities both at the border and in cities nationwide have struggled to handle recent surges. The party may also be losing favor with Hispanic voters amid disenchantment with Biden. But Padilla, in a series of interviews with The Associated Press, expressed a deep reserve of optimism about his party’s ability to win support both from and for immigrant communities.

“Don’t be afraid, don’t be reluctant to talk about immigration. Lean into it,” Padilla said. “Because number one, it’s the morally right thing to do. Number two, it is key to the strength, the security and the future of our country.”

The senator has tried to anchor his fellow Democrats to that stance even as the politics of immigration grow increasingly toxic. Donald Trump, the presumptive Republican presidential nominee, has said immigrants who enter the U.S. illegally are “poisoning the blood” of the country and accused Biden of allowing a “bloodbath” at the southern border. Biden, meanwhile, has shifted to the right at times in both the policies and language he is willing to use as illegal border crossings become a vulnerability for his reelection bid.

Such was the case when Biden, during his State of the Union address, entered into an unscripted exchange with Rep. Marjorie Taylor Greene, a Republican of Georgia, and referred to a Venezuelan man accused of killing a nursing student in Georgia as an “illegal” — a term anathema to immigration rights advocates.

After the speech, Padilla discussed the moment with Rep. Tony Cárdenas in the apartment they share in Washington. The men, who have known each other since their earliest days in Los Angeles politics, now form a political odd couple while away from their families in California. Padilla towers over many in the Capitol with his height and usually speaks in measured tones, while Cárdenas, shorter in stature, is known to come to tears during debates and worries sometimes his voice carries into the neighboring apartment.

“Usually I’m talking in 20 sentences by the time he’ll get his one or two sentences,” Cárdenas said. “He’ll say what I’m saying pretty much, but much more calmly, much more methodically.”

And that night, Cárdenas said, their conversation turned to how they wanted politicians to avoid labeling migrants as “illegals” because it deprived them of dignity.

Padilla told him he would call the White House.

“He’s is the kind of person who steps in and steps up, and, you know, he’s tactical about it,” Cárdenas said.

It’s a difficult role to play, especially as Democrats try to shore up what’s seen as a weakness on border security in the battleground states that will determine control of the White House and Congress.

Even in California, Republicans have been emboldened on immigration as they try to reassert statewide relevance, said Mark Meuser, a lawyer who lost elections against Padilla for the Senate in 2022 and California Secretary of State in 2018. He argued top California Democrats like Padilla “are driving hard towards the extreme edges of their party.”

Padilla has urged the president and fellow Democrats to hold firm to the position that border enforcement measures be paired with reforms for immigrants who are already in the country. Padilla expressed frustration with how some Democrats, including Biden, did not keep immigration reforms, such as a pathway to citizenship for those who entered the U.S. illegally as children, a top priority during a negotiation earlier this year with Senate Republicans on border security.

During those negotiations, Padilla asserted himself as the leader of congressional opposition from the left: He pulled Biden aside for one-on-one conversations to warn against the changes, spoke forcefully at rallies advocating for immigrant rights and organized a call with top White House aides and the Congressional Hispanic Caucus. Padilla, along with four other Democratic-aligned senators, eventually voted against advancing the package, ensuring its failure as Republicans also rejected it.

“He is a lone voice but it is a courageous voice in the Senate,” said Vanessa Cardenas, who leads the immigration advocacy organization America’s Voice.

It’s been a quick ascent for Padilla, who is just beginning his fourth year in Congress, and comes as little surprise to those who have known him since his days in California politics.

“What he’s always been brilliant at is being able to navigate the space, bring people together, be a constructive player,” said John A. Pérez, who was the California Assembly Speaker while Padilla was in the state Senate. “With Alex you don’t get criticism without an alternative.”

Padilla was also known as a determined and effective negotiator. While he was on the Los Angeles City Council, Padilla negotiated a statewide deal with then-Gov. Arnold Schwarzenegger to send more funding to local governments. What was supposed to be a one-day meeting turned into a ten-day, around-the-clock negotiation in Sacramento. Padilla quickly exhausted his wardrobe and resorted to washing his socks in a sink, said Mike Madrid, a Republican strategist who worked with Padilla on the League of Cities. They got the compromises they wanted.

Now that Padilla is involved in the immigration policy debate, Madrid said “the politics have never demanded border security more and immigration reform less.”

But he conceded that he could be proven wrong: “If there is any one person in Washington that could make that deal happen, it would be Alex Padilla.”

And for Padilla, it’s the very reason he entered politics in the first place.

When he graduated in 1994 with an engineering degree from the Massachusetts Institute of Technology, it was a dream fulfilled for his parents — his father a short order cook and his mother a house cleaner. But he was soon drawn into politics as the state’s attention turned to Proposition 187, a 1994 ballot measure that was approved to deny education, health care and other non-emergency services to immigrants who entered the country illegally.

It was branded by supporters as the Save Our State Initiative. Padilla still remembers the ads for the campaign.

“Trying to try to blame a downward economy on the hardest working people that I know was offensive and an outrage,” he said.

Now he sees parallels between California in the 1990s, which approved the ballot measure but then had it invalidated in federal court, and the wider country today: changing demographics, economic uncertainty and political opportunists “scapegoating” immigrants.

Yet it also spurred the state’s Latinos to get involved politically. To Padilla, there’s no coincidence that California, the state with the most immigrants, now boasts the nation’s largest economy and is a stronghold for Democrats.

One of Padilla’s first jobs in politics was managing the state assembly campaign for Cárdenas, who is about a decade older than Padilla and grew up a few blocks from him in Pacoima, a neighborhood in the San Fernando Valley.

The campaign started as an unlikely bid for two political neophytes trying to get the area to elect a Latino for the first time. Cárdenas remembered Padilla working so hard on the campaign trail that he fell asleep standing up as they debriefed one night.

“We were literally laughed out of people’s offices at the time,” Padilla said. Still, Cárdenas won.

Padilla went on to work for the late Sen. Dianne Feinstein and manage other local campaigns until he ran for Los Angeles City Council at the age of 26. Padilla rose quickly in the council, becoming its president at the age of 28. And for two days following the Sept. 11, 2001, terrorist attacks, Padilla oversaw the emergency response while then-Mayor James Hahn was stranded across the country in Washington. Padilla gave interviews in both English and Spanish to reassure the city’s population.

But before he was elected to his first office, he faced skepticism about his age. Cárdenas said his bid for the council seat only took off when Padilla closed a debate by invoking a phrase often used in the hardscrabble community of the San Fernando Valley: “No te rajes.” Don’t give up.