Dianne Feinstein, who made history as California’s inaugural female senator and went on to secure six consecutive terms, the longest tenure of any woman in Senate history, has passed away at the age of 90. Her political journey was profoundly impacted by the assassinations of two fellow senators.

According to her office, Feinstein passed away on Thursday night at her residence in Washington, with the cause of death undisclosed. Remarkably, she had cast her vote earlier that same day.

James Sauls, her chief of staff, stated, “There are few women who can be called senator, chairman, mayor, wife, mom, and grandmother.” He went on to describe Feinstein as “a force of nature who made an incredible impact on our country and her home state.”

Sauls added, “She left a legacy that is undeniable and extraordinary. There is much to say about who she was and what she did, but for now, we are going to grieve the passing of our beloved boss, mentor, and friend.”

President Joe Biden, in his statement, referred to Feinstein as a “pioneering American,” a “true friend,” and “a role model for so many.”

Throughout her thirty-year tenure in the Senate, Feinstein evolved from a trailblazing member of the Democratic Party’s progressive front, advocating for causes such as the legalization of same-sex marriage and a ban on assault-style weapons, to one of Washington’s established figures, earning respect from lawmakers across the political spectrum but also facing mounting criticism from progressive outsiders who contended that she was unwilling to step aside for the next generation.

In her final years, concerns about her mental and physical well-being began to overshadow her work on Capitol Hill, despite her assertions of continued vitality as a public servant. These concerns were exacerbated by her hospitalizations and reports of episodes of confusion, among other issues.

Earlier this year, when announcing her intention to retire at the conclusion of her current term in 2025, Feinstein stated, “Each of us was sent here to solve problems. That’s what I’ve done for the last 30 years, and that’s what I plan to do for the next two years. My thanks to the people of California for allowing me to serve them.”

California Governor Gavin Newsom, also a Democrat, will be tasked with appointing someone to fulfill the remainder of Feinstein’s term, leading up to the 2024 election to determine her successor.

He has committed to appointing a Black woman, a historic move that would make her only the third Black woman to serve as a senator in U.S. history. However, Newsom has also indicated that he will not select any of the candidates from the current Democratic primary race, which includes Rep. Barbara Lee.

Journalist Rebecca Traister, who extensively profiled Feinstein for New York magazine, shared her perspective with ABC News for this obituary. Traister believed that Feinstein’s political approach was rooted more in a commitment to upholding rules and order than in adhering to an absolutist ideology.

While Feinstein’s political stances evolved over time, her fundamental view of her role remained consistent. According to Traister, Feinstein saw herself “as somebody who was within these institutions to uphold the rules.”

What struck Traister most about Feinstein was her unwavering dedication to institutional integrity, extending beyond the realm of politics. Traister recounted an example from the early 1960s, prior to Roe v. Wade, when Feinstein was involved in determining penalties for abortion providers during her tenure on a women’s sentencing board.

Feinstein later remarked that she encountered “not medical people — these were truly the coat-hanger type of abortions.” Even as a pro-abortion access advocate during her college years, Feinstein reportedly assisted a woman in reaching Mexico, where abortion was legal.

“She believed in civic and political control and order, and I would say that is the defining feature of her life in politics,” Traister said, adding, “Sometimes that led her to positions that were on the left and sometimes it led her to positions that were on the right.”

In the waning years of her political tenure, some members of Feinstein’s own party vocally urged her to consider retirement. However, she also had staunch defenders who came to her support. In 2017, then-House Speaker Nancy Pelosi lauded her as a “strong voice and a staunch advocate for the people of California.”

During Feinstein’s most recent Senate campaign, the California Democratic Party threw its support behind challenger Kevin de León. At the time, León positioned himself as “a new voice, a new change representative of California today, not of the past.”

Nevertheless, Feinstein secured victory in a landslide, amassing approximately one million more votes than her opponent. Despite her resounding win, discontent within her party persisted.

In the waning years of her political tenure, some members of Feinstein’s own party vocally urged her to consider retirement. However, she also had staunch defenders who came to her support. In 2017, then-House Speaker Nancy Pelosi lauded her as a “strong voice and a staunch advocate for the people of California.”

Feinstein’s impending retirement became overshadowed by her health challenges in 2023. She spent three months in California recovering from shingles, which resulted in brain inflammation and Ramsay Hunt syndrome, affecting her facial nerves. This extended absence temporarily halted the Judiciary Committee’s ability to confirm nominees, on which Feinstein served.

Congressman Ro Khanna, among others, called for her resignation, but she remained steadfast in her role.

Surviving her is her daughter, Katherine. Her third husband, wealthy investor Richard Blum, whom she married in 1980, passed away in 2022 after a cancer diagnosis.

Mark Barabak, an LA Times columnist, noted that Feinstein’s tenacity contributed as much to her success as the controversies that marked the end of her career. He described her as “very determined, stubborn, and dogged,” emphasizing that she consistently demonstrated she would not be easily influenced. He remarked, “This aligns with who she has been throughout her entire career and public life.”