When both East Bay Rep. Eric Swalwell and billionaire San Francisco activist Tom Steyer turned up at the Iowa State Fair this month, it became official: One in every five Californians is thinking about running for president in 2020.

That means it is time to take a waaay too early look at the field of Golden State Democrats sniffing a run for the White House. We asked several political consultants, Republicans and Democrats, to break down their strengths and weaknesses. We granted the operatives anonymity so they could speak freely — and not lose business should any of these candidates actually run.

One thing the political pros all emphasized: Nobody knows who the heck these would-be commanders-in-chief are, yet. Not even Kamala Harris, senator from the nation’s largest state, who is at the top of every pundit’s short list of likely candidates. In a Harvard CAPS/Harris poll of potential 2020 candidates taken in June, Harris was the choice of only 2 percent of the respondents.

And Harris was at the top of potential California candidates. Why? Because the pollsters didn’t even ask about any others. So with that in mind, let’s break down the sniffers:

Kamala Harris, senator

Telling signs: Raised $5 million for other Senate candidates; invested in her online and social media outreach and national fundraising operation. And the flat-out giveaway: Her memoir is due out in January.

Strengths: “She has a lot of charisma, is smart and is well-known to Democratic activists,” said a Democratic operative. “And she’s telegenic.” The former San Francisco district attorney and state attorney general “has been a prosecutor, so she’s tough.” With a seat on the Senate Judiciary and Intelligence committees, she will get tons of media attention, particularly during the Supreme Court confirmation hearings for Brett Kavanaugh.

Weaknesses: “She’s a liberal California senator,” said a Democratic operative. “Democrats elsewhere may love that in their hearts, but in their heads they may say, ‘Give me a Midwestern governor.’”

“There’s an authenticity problem,” said a Republican. “I could see eating a corn dog in Iowa with (Los Angeles Mayor Eric) Garcetti. But not her.”

Is she running? “99 percent,” said a GOP operative.

Eric Garcetti, L.A. mayor

Telling signs: Campaigned for the mayor of Manchester, N.H., and headlined a fundraiser for the South Carolina Democratic Party fundraiser. New Hampshire and South Carolina are early primary states.

Strengths: Leads a city that’s more populous than 23 states and can claim outsider status because the city isn’t Washington. “Mayors are deal-makers,” said a Republican, “and he can talk about passing that bond,” a $120 billion transportation measure that L.A. County voters approved in 2016.

Plus, said a Democrat, “he has this hipster, cool-kid thing going. Plays jazz piano.”

Weaknesses: The first attack ad on Garcetti writes itself: The camera pans the 50,000 people living on the streets of his city. “If you’re going to run as a big-city mayor who gets things done, L.A. is a city that has a lot of problems,” said a Democrat.

Is he running? “Oh, come on,” said a Democrat. “No L.A. mayor raises money for South Carolina Democrats out of the kindness of their heart.”

Tom Steyer, activist

Telling signs: The former hedge-fund manager is spending $120 million to turn out Democrats for midterm elections. He stars in commercials calling for President Trump’s impeachment.

Strengths: “His wallet,” said a Republican. “He could hire field staff in all the early states.” And the idea of impeaching Trump is popular with the Democratic base that votes in primaries.

Weaknesses: “Three words: Hedge-fund billionaire,” said a Democrat. “Democrats will never support a rich guy.”

Despite spending millions of dollars on TV ads that feature him, he’s got no name recognition. “Those ads have never explained who Tom Steyer is,” another Democrat said.

Is he running? “He’s not,” said a Democrat. “He’s teased but he’s backed away twice (to run for California governor and senator). He just likes the teasing part.”

Adam Schiff, congressman

Telling signs: The Burbank congressman has made hundreds of appearances on cable news shows as the ranking Democrat on the House Intelligence Committee.

Strengths: “He’s a down-to-earth, serious counterweight to Donald Trump,” said a Democrat. “He’s got a nerdy appeal.”

Seems “authentic,” said a Republican.

Weaknesses: “If your portal into the race is MSNBC appearances, that’s only going to take you so far,” said a Democrat. “He’s kind of one-dimensional — although that one dimension is great.”

A Republican said Schiff “may be on TV a lot, but he’s still Joe Blow congressman from L.A. He’s not black or Latino or super-liberal. So what’s his constituency in the early states?”

Is he running? “Nah,” said a Republican. If Democrats retake the House, “then he leads the Intelligence Committee. And those hearings are going to be amazing. It’s a bad look if he keeps taking off to Iowa.”

Eric Swalwell, congressman

Telling signs: The Dublin Democrat has made 10 trips to Iowa and is a cable TV news regular.

Strengths: “With all those TV appearances, he can go to Iowa as this good-looking former prosecutor who was born in Iowa,” said a Democrat. “He has a forcefulness and clarity about the state of the country that’s appealing now.”

Weaknesses: “I had to Google him,” said a Republican.

Is he running? “Nah. He’s building the brand and the network for something else,” said a Democrat.

Like “a cabinet post,” said another Democrat. “He’s so young (37), he could run in 12 years and not be old for a president.”

Joe Garofoli is The San Francisco Chronicle’s senior political writer. Email: jgarofoli@sfchronicle.com Twitter: @joegarofoli