Soon after Kamala Harris was sworn in as California’s attorney general in 2011, she traveled to Washington to meet with colleagues at the U.S. Department of Justice. There, she met Brian Nelson, a promising young lawyer who had recently been promoted to deputy chief of staff of the national security division. 

Harris and Nelson clicked, and she got to work convincing him to move across the country to work for her. She succeeded. Soon after, Nelson moved to Los Angeles, eventually rising to become general counsel at the California Department of Justice under Harris.

“He had a nice job, a very substantial job in Main Justice, but she could be very persuasive,” said Nathan Barankin, who served as Harris’ chief of staff when she was attorney general and in her Senate office. 

Now, Harris has tapped Nelson as a senior adviser for policy, making him one of the first major campaign hires from Harris’ West Coast inner circle — not a holdover from the campaign apparatus built by President Joe Biden, nor one of the Obama-era strategists brought on by Harris to capitalize on Democrats’ grassroots energy. 

“Brian was one of those guys who came over early in her term, and he very quickly just became one of her most trusted confidants in that office,” said Brian Brokaw, a political consultant in California who managed Harris’ campaign for attorney general in 2010. 

Nelson worked closely with Harris on legal matters touching on a range of issues, including health care, environmental policy and immigration. His best-known work in that time was serving as a key deputy to Harris during negotiations on a settlement with major banks over the predatory mortgages that touched off the Great Recession. Harris felt the multibillion-dollar settlement between the banks, states and the federal government didn’t go far enough — putting her at odds with the Obama administration, but ultimately leading her to seek more funding for Californians who had been impacted.

In Washington, Nelson is better known in the national security world. A Los Angeles native, Nelson moved back to Washington at the start of the Biden-Harris administration at his former boss’s urging to serve as a political appointee at the Treasury Department, where he oversaw U.S. sanctions policy from late 2021 to July 2024, when he left to join the Harris campaign. 

“In D.C. jobs, everyone can sort of get pigeonholed a little bit, so when he’s worked in the administrations of the Obama world and up until recently the Biden world, it was all national security-related work,” said Barankin. “He has a depth and breadth to his policy chops that maybe a lot of people outside of D.C. are unaware of, but [Harris is] certainly not clueless about.” 

Nelson was confirmed as Treasury undersecretary for terrorism and financial intelligence along party lines, with Harris casting a tie-breaking vote in the Senate. Republicans objected to his nomination in protest of the Biden administration’s decision in 2021 not to sanction the firm managing Russia’s Nord Stream 2 gas pipeline. 

“I’ve seen Brian’s work up close and he’s a true public servant. We wish him the best in this new role,” Harris wrote on social media after she swore him in to his position. 

Two months later, in February 2022, the U.S. finally imposed the Nord Stream 2 sanctions. The next day, Russia invaded Ukraine, and Nelson in turn helped implement a massive sanctions regime against Russia. 

Harris brought Nelson onto her campaign because she trusts him, first and foremost. It wasn’t a staffing pick designed to send a specific policy message. Still, Nelson remaining in that role at Treasury through an unprecedented sanctions policy targeting Russia says something about what he cares about, and how Harris views foreign policy.

“He is somebody who I would expect to be advising the vice president on holding firm on sanctions and the importance of multilateral alliances when it comes to sanctions, coordinating with the EU and not allowing Russia to work around the sanctions,” said Adam Szubin, who held the same position at Treasury in the Obama administration. 

A big part of Nelson’s job at Treasury was “diplomatic,” according to Szubin, “in terms of trying to corral other countries and trying to push the less compliant countries.” Ten days after the Oct. 7 attacks in Israel, Nelson spoke about the Treasury Department’s efforts to target Hamas’ financing in an address at an anti-money laundering conference. 

“The stakes could not be clearer. Hamas’ unconscionable and heart-wrenching attacks on innocent civilians show that we must redouble our efforts to deny terrorists access to funding streams and root out bad actors from across the global financial system,” Nelson said. “The U.S. is unequivocal in its support for Israel in the face of these atrocities perpetrated by Hamas. We cannot, and we will not, tolerate money flowing through the international system for Hamas’ terrorist activity, and there is clearly more work to be done.”

A senior Biden administration official described Nelson as “an instrumental figure in imposing punishing sanctions on terrorist groups and our adversaries, as part of our effort to support Israel’s right to defend itself against Iran and Iran-backed terrorist groups.” The Harris campaign declined to comment.

Nelson’s current role advising Harris on her presidential run is almost certainly not the outcome he expected when he jumped shop from Washington to L.A. more than a decade ago. After he left California’s Department of Justice, he joined the organization behind L.A.’s 2028 Olympic bid, ultimately serving as chief legal officer for LA28. But he always stayed close to Harris.

“I don’t think anybody went to work for her thinking that they were going to work for a future president of the United States. But if you had told any of us back then that’s what the future would hold, I don’t think it would have necessarily been a surprise to anybody,” said Brokaw. 

Nelson “joined the [Biden] administration, but he was at Treasury, not directly in her world” added Brokaw. “I think that just speaks to — he is part of her family, and even if he is working for somebody else at the time, he is immensely loyal to her.”