Dianne Feinstein is retiring. Could Adam Schiff replace her?

Adam Schiff was everywhere during the Donald Trump years. Whether investigating Russian interference in the 2016 election and potential ties between Trump and Russia on the House Intelligence Committee, prosecuting the case to impeach Trump for his pressure on Ukraine to dig up dirt on Joe Biden, or questioning witnesses as part of the January 6 committee, Schiff has been a ubiquitous face of anti-Trump Democrats for the better part of the last decade.

Now, freshly booted from the committee he once ran, he’s running for Senate in California and answering Rep. Katie Porter’s call for a progressive Senate showdown in one of the most liberal states in the country. His run will become a test of the staying power of Trump-inspired rage from the last six years.

“When a dangerous demagogue tried to undermine our democracy, I wasn’t about to let him,” Schiff says in a video launching his campaign on Twitter. “After all that, I wish I could say the threat of MAGA extremists is over. It is not.”

Schiff is entering a field that might get more crowded. Porter was the first California Democrat to announce her campaign earlier this month, kicking off a contest that seemed to be on hold until the current incumbent, Sen. Dianne Feinstein, made up her mind about retiring. Feinstein will be 91 in 2024 and is the longest-serving Democrat in the Senate at the moment, but on February 14, she announced she won’t seek another term.

Other California members of Congress are still mulling runs: Northern California Rep. Barbara Lee reportedly told colleagues in the Congressional Black Caucus that she was preparing to run, while fellow Bay Area Rep. Ro Khanna is still making up his mind.

A few of Porter’s early progressive endorsers have already hit back at Schiff for not being progressive enough and for previously accepting PAC money from “Big Oil, Big Pharma, payday lenders, and Wall St banks.” Other criticisms from California progressives reveal one of the central tensions of Schiff’s nascent campaign: how to run an appealing primary race when his greatest asset is a backward-looking appeal to anti-Trump, #Resistance-era nostalgia instead of a future-oriented agenda backed by a track record of congressional advocacy, like Porter, Khanna, and Lee.

The Democrats who do end up running will have to find ways to distinguish themselves, given that they all occupy space on the Democratic Party’s left flank.

Lee is an old-school, anti-establishment liberal with widespread name recognition in the Bay Area. Khanna has built more of a name for himself as a technocrat and wonk in the tech, antitrust, and economic realm, and co-chaired Bernie Sanders’s 2020 presidential campaign. Porter comes from the Elizabeth Warren lane of the party. But Schiff’s congressional identity has been shaped by his establishment ties.

A member of the New Democrat Coalition in the House, he’s not as left-leaning as some of his rivals, but he’s no centrist and has occupied a lane as a fairly standard liberal Democrat, frequently backing increases in defense spending, support for Israel, and press freedoms abroad.

Schiff might not have to lean too heavily on those parts of his résumé, particularly with Trump’s third presidential bid underway. Porter’s internal polling shows that Schiff will likely be her biggest challenge, easily landing a spot in the general election (California’s open primary system moves the top two vote-getters in the June primary on to a general election regardless of party).

That’s not to say Schiff will cruise to the general if the field grows crowded. To succeed, he will need to make inroads with the state’s working-class Latino, Black, and Asian voters, and win over Northern California progressives and the white college-educated voters who are likely to make up the bulk of Porter’s support. Unlike Porter and his other potential opponents, who are both people of color, Schiff won’t be able to appeal to personal identity or representation. A victory for him would also be a loss for gender representation in the Senate, where nearly 70 percent of members are white men.

The state’s racially and ideologically diverse population will make this one of the most competitive races of 2024. Though Democrats outnumber Republicans nearly two to one in the state, progressive candidates aren’t guaranteed success, something Schiff could possibly capitalize on if he can appeal to the many moderates who make up the general electorate. Despite its portrayal in popular media as a state run amok with ultra-progressive, college-educated ideals, California is not among the states with the highest percentage of college-educated residents.

That means finding a message that resonates with Democrats of various ideologies, education levels, and identities. Whether a message focused on defending democracy and standing up to Trump does that will be borne out with time. At least one star from the Trump years has already turned that message into political power: Dan Goldman, the lead attorney in that first impeachment trial that Schiff led, won in a crowded field of progressives and liberals running in the 10th Congressional District of New York’s Democratic primary and is now a member of Congress.

But winning in an electorate of 750,000 New Yorkers is one thing. Convincing a plurality of 27 million eligible California voters is another.

Update, February 14, 5:10 pm ET: This piece was originally published on January 26 and has been updated with details of Sen. Feinstein’s announcement that she would not seek another term.