His constituents of Latino, Korean, and Armenian descent wait in his front office, waiting for a moment to share their fears about Trump with California's most powerful state lawmaker.
"There's a lot of angst and anxiety, and they're looking for answers. What does January 20, 2017, mean?" said de León, California's first Latino elected leader of the state Senate in more than a century.
He's sharing with them the same unwavering message: "We don't want to fight. We're not looking for a fight. But if necessary, we will fight to protect the values of California. Given what I've seen so far with regard to the Cabinet selections, there probably is going to be a fight around the corner very, very soon."
The looming battle pits America's largest and most progressive state against the incoming Trump administration. California is 13% of the US economy, with a GDP bigger than Brazil, growing faster than the economies of Japan, Germany or the UK. The state, which is 40% Latino, voted in more Democrats to the state legislature (where it holds a two-thirds majority in both houses) and is growing more progressive on issues such as the environment, minimum wage, gay rights and immigration.
California's Democratic supermajority mandate and its economic heft is what de León will leverage against Trump. De Leon, with Assembly Speaker Anthony Rendon, introduced sweeping state legislation to blunt Trump's expected immigration policies.
The measures, expected to pass early in the new year, would offer undocumented immigrants more access to legal help and would further spell out the limits of local law enforcement's cooperation with federal immigration agents. De León acknowledges the limits of state action, but pledges to protect the families split along immigration status.
"We can't prohibit them (the federal government) from doing what they want to do, if they want to do mass deportations. But we surely don't have to help them," said de León.
A message left with the Trump transition team was not immediately returned.
Another option to slow Trump is to file lawsuits to blunt federal action.
At stake in this opening salvo of California vs. DC is hundreds of millions in federal funding. Trump has pledged to cut federal funding for so-called "sanctuary" cities. With all major California cities declaring themselves sanctuaries, from Los Angeles to San Francisco to Sacramento, de León said, "If you punish California, you're punishing the rest of the country. We're 13% of the overall GDP of this nation. To go out of your way to hurt California, ends up hurting the nation. It's my hope that there won't be political retribution, that a Trump administration won't deny funds because of this undefined sanctuary city or state status."
California, while overwhelmingly Democratic, did have 4 million people vote for Trump. Those voters want federal immigration laws followed, said Robin Hvidston, executive director of We the People Rising, a conservative grassroots group in Los Angeles. She said state lawmakers are enacting protective measures before Trump has had a chance to act, creating "hysteria in our state."
"We should be a state that upholds and respects the law," said Hvidston. "That's what our lawmakers should be focused on in Sacramento, not working with or encouraging people in our state who are here illegally."
De León is hardly alone in his positions in California, joined by mayors and police chiefs across the state and by leaders in Sacramento. Both leaders of the chambers of the state legislature are Latino, as is the incoming state attorney general, Xavier Becerra.
De León also has a uniquely personal view of undocumented immigration: his mother was undocumented. A single mother of three with a third-grade education, she brought her son on San Diego public buses to the mansions of La Jolla, California, where she cleaned houses.
That boy would grow up to enter California politics, informed by his upbringing as he's spent his legislative career pushing progressive measures on the environment, worker's and women's rights, and immigration.
"It is personal when the incoming head of state and others that surround him demonize and scapegoat and pit one group against one another for a political objective," said de León.
The state Senate leader also pledges California will lead the opposition for the rest of the country's voters who do not support Trump's agenda.
"They can look to California to lead the way," he said.