With Senator Dianne Feinstein’s retirement, the party is gearing up for a clash on issues including gender, race, ideology and even geography.LOS ANGELES — Even before Senator Dianne Feinstein of California announced her retirement on Tuesday, the race taking shape for the seat she has held since November 1992 was poised to become one of the most competitive and expensive in the country. Now, the incumbent’s imminent departure has raised an urgent question for California Democrats: Whose turn is it?Two members of Congress have jumped in, with a third expected to join soon, and the 2024 contest is already revealing ideological, generational, regional and racial divides within the party in America’s most populous — and arguably bluest — state.Representatives Katie Porter and Adam Schiff, two Democrats who amassed national profiles opposing former President Donald J. Trump and his administration officials, have announced campaigns to replace Ms. Feinstein, 89, who said on Tuesday that she would retire at the end of her term. Ms. Porter and Mr. Schiff have spent recent weeks aggressively accruing major endorsements, reporting seven-figure fund-raising hauls and crisscrossing the state to court voters and donors.And Representative Barbara Lee, the highest-ranking Black woman appointed to Democratic leadership, is planning to join the field before the end of Black History Month. No Black women are in the Senate, and there have been only two in the chamber’s more-than-230-year history: Carol Moseley Braun of Illinois, who served one term in the 1990s, and Kamala Harris, who became vice president in 2021.Representative Adam Schiff has already raised millions for the Senate race, and he has a notable endorsement: Nancy Pelosi, the former speaker.Mario Tama/Getty ImagesThe race for Ms. Feinstein’s seat is unlikely to determine control of the Senate — at least five other states will be fiercely contested by the two parties. In deep-blue California, Republicans have become all but irrelevant in the higher echelons of government. But the departure of a defining figure of the state’s politics opens up a seat with outsize influence because of the size of California’s economy and population.The next senator will help oversee a state that has been transformed during Ms. Feinstein’s 30 years in office. Its Latino population has become its largest demographic. Its Democratic Party is trying to redefine itself in the aftermath of the Trump era, and the divide between a wealthier and whiter San Francisco and a poorer and more diverse Los Angeles has only widened.More on CaliforniaA Settlement: San Mateo County has agreed to pay $4.5 million to the family of a Black man who died in 2018 after a deputy used a Taser on him during a struggle that began when officers saw him jaywalking.Covid State of Emergency: The state’s coronavirus emergency declaration, which gave Gov. Gavin Newsom broad powers to slow the spread of the virus, is set to expire on Feb. 28.In the Wake of Tragedy: California is reeling after back-to-back mass shootings in Monterey Park and Half Moon Bay.Medical Misinformation: A federal judge has temporarily blocked enforcement of a new law allowing regulators to punish doctors for spreading false or misleading information about Covid-19.Ms. Porter, Mr. Schiff and Ms. Lee would all usher in an ideological shift, one decidedly to the left of Ms. Feinstein, who in recent years has drawn anger from the left flank of her party over her bipartisan approach and deference to Trump-appointed Supreme Court justices. Ms. Porter and Ms. Lee have served in leadership of the Congressional Progressive Caucus, and though Mr. Schiff has not joined the group, he has increasingly struck progressive tones after once counting himself a member of the Blue Dogs, a group of conservative Democrats. A victory for either Ms. Porter, 49, or Mr. Schiff, 62, would signal a long-awaited break in a generational logjam, as well as a change in regional power.Representative Katie Porter has had both substantial fund-raising and the endorsement of Senator Elizabeth Warren.Brian Snyder/ReutersUntil recently, the Bay Area has dominated the state’s politics, producing some of its most marquee figures, including Ms. Feinstein, Ms. Harris, the former House Speaker Nancy Pelosi and Gov. Gavin Newsom. Ms. Porter’s district is in Orange County, and Mr. Schiff represents a northern slice of Los Angeles. Given California’s demographic shifts, some Democrats believe the state’s next senator should also capture its growing racial and ethnic diversity.It is not the first time that California has been at a similar inflection point. When Ms. Feinstein first ran, in 1992, women were outraged at the treatment of Anita Hill during the confirmation hearings for Justice Clarence Thomas. Four women won Senate seats that year in a watershed moment for American politics, and California became the first state in the nation to be represented by two female senators.Nearly three decades later, after the 2020 presidential election, women’s groups and Black leaders lobbied Gov. Gavin Newsom of California to choose a Black woman to fill the seat vacated by Kamala Harris, who had been the only Black woman in the upper chamber until she was elected as vice president. Mr. Newsom ultimately named Senator Alex Padilla, the state’s first Latino senator and its secretary of state at the time. But Mr. Newsom pledged to choose a Black woman to fill Ms. Feinstein’s seat should she retire before her term ended. The former Senator Barbara Boxer, who won the 1992 election along with Ms. Feinstein and served in the upper chamber until she chose not to seek re-election in 2016, played up the highly qualified bench of candidates and said they would all have the chance to make their cases. Ms. Boxer was still weighing her endorsement, but she said she believed the moment called for a strong progressive unafraid “to fight some of the forces that have been unleashed by Donald Trump.”“We are in one of those moments in history where we need the toughest leaders and those who are really not fearful,” she said.Even before Ms. Feinstein announced her plans to step away after her term ends in January 2025, California political strategists and observers had begun to debate just who that progressive might be. This month, former House Speaker Nancy Pelosi and 14 other members of the California delegation said they would endorse Mr. Schiff if Ms. Feinstein chose to retire.There was not much surprise at Ms. Pelosi’s endorsement of Mr. Schiff, a loyal lieutenant whom she elevated to some of the toughest jobs in Congress. But Ms. Pelosi rarely weighs in on Democrat-on-Democrat races, and the timing was unusual because the election is not until November 2024. Asked why she believed it was important to endorse Mr. Schiff early, Ms. Pelosi said she believed he would make “a fabulous senator.”“And I did what I wanted to do,” she said in a brief interview last week, as she briskly left the House gallery.Ms. Boxer called Ms. Pelosi’s decision “brave” and “very typical Nancy.” “She is straightforward with people,” Ms. Boxer said.But the move drew criticism, too. Aimee Allison, the founder and president of She the People, a political group that supports progressive women of color in politics, called the decision “cynical” because it curtailed the path to victory for a Black candidate with a stellar party track record. She was referring to Ms. Lee, who has been known for progressive stances, and who was the sole lawmaker in Congress to vote against invading Afghanistan after the Sept. 11 attacks.Women of color and Black women in particular face barriers to fund-raising and support from the Democratic establishment, Ms. Allison said. “They have hashtags to thank us,” she said of Democrats. “But Black, Latina, Asian American women — AAPI women — Native American women, we want to be represented.”Representative Barbara Lee is expected to join the Senate race soon. She will be at a fund-raising disadvantage at the outset.Sarahbeth Maney for The New York TimesIn interviews last week, some Democratic voters were split on how much they would factor issues of race and gender into their decisions, with some arguing that the state’s leadership was already diverse and others contending that its highest ranks were not diverse enough. Others pointed to the profanity-laced audio recordings of Latino City Council members mocking people in racist terms as evidence that even representation based on identity was no guarantee of an inclusive perspective.Mr. Schiff and Ms. Porter, for their part, acknowledged the importance of issues of race and gender in the Senate race, though they said how much they factored into the result would ultimately be up to voters. The two also have also sought to draw sharp contrasts between their candidacies.On a chilly, overcast Saturday, Mr. Schiff, a former prosecutor who led Mr. Trump’s first impeachment trial, billed himself as a staunch defender of democracy and a progressive leader committed to creating jobs and tackling climate and gun safety issues. In Congress, he said, he had dedicated himself to becoming an expert on national security issues, exposing torture and working to overhaul the nation’s surveillance system.“I took on these fights because they mattered, because they made Americans’ lives better, our system more just, our kids’ future more secure,” he said before some 600 supporters at the union hall parking lot in Burbank, where he launched his first run for Congress more than two decades ago. “And then I took on the biggest fight of my life against Donald J. Trump.”At a parks and recreation center in Huntington Park, where Ms. Porter met with Latino environmental justice activists and community leaders on Friday, the congresswoman described herself as a political newcomer and a single mother who had never taken corporate PAC money and who would be willing to challenge both parties on issues like child care and paid family leave.Ms. Porter, who studied under Elizabeth Warren at Harvard, garnered national prominence as she grilled corporate executives and government officials in congressional hearings, often turning to a handy whiteboard to explain complex topics. She pointed to her victories in a competitive swing district as evidence that she could win without compromising her progressive values.“I have had three really hard races and have won every one of them,” she said in an interview.Karina Macias, a Huntington Park council member who had taken a walk through the neighborhood with Ms. Porter that morning, said she had not made an endorsement in the race.“Obviously, diversity is important, being a Latina woman myself,” she said. “For me, it is that, but also who is coming to talk to these cities that have been screaming for years to get some attention from Congress to make sure that we get that discussion on our issues.” More