California and its 548 convention delegates may be the biggest prize of the Democratic primary season, but the party’s two presidential hopefuls are taking very different routes to a potential June 7 victory.

Former Secretary of State Hillary Clinton, the Democratic front-runner, wants to win, but in a way that doesn’t alienate Vermont Sen. Bernie Sanders’ supporters, because she’ll need them in a fall campaign.

“We don’t want a scorched-earth campaign, especially when the Democratic nomination is all but settled,” said Dan Newman, whose San Francisco political consulting firm is working for Clinton. “We don’t want to create obstacles to unifying to stop (presumptive GOP nominee Donald) Trump in November.”

But for Sanders, who has acknowledged that his path to the nomination is both steep and narrow, California is a must-win state if he’s going to convince unpledged convention delegates that he’s the Democrats’ best hope of beating Trump.

“We’re running a very aggressive schedule,” said Robert Becker, Sanders’ California campaign director. “We’re going to work the state pretty hard, and we’re not conceding anything.”

For Sanders, that’s meant a grueling schedule of high-profile rallies across the state, with the candidate repeating his familiar cry for a political revolution against what he calls a rigged economy and corrupt politics. He’s been drawing thousands of people at each stop.

“We’re probably going to do a couple dozen of rallies,” said Becker, who also ran Sanders’ efforts in Iowa and Michigan. “We’ve found that in states like California ... we need to use our No. 1 organizing tool, which is Bernie Sanders.”

Seeking superdelegates

Before his rally in San Jose on Wednesday, in sweltering afternoon heat, Sanders told The Chronicle that part of the reason he’s holding rallies around the state is to flash his power to the unpledged superdelegates he wants to woo at the national convention in July.

“Hillary Clinton cannot hold rallies like this. She will not have 5,000 people coming out,” Sanders said. “The significance is that when people come out on a hot Wednesday, they are prepared to engage in politics. That means to be part of a grassroots movement. And that translates into high turnouts in November,” which is needed for a Democratic victory.

Besides revving up supporters and providing a vision of excitement and momentum for undecided voters, campaign volunteers use the jam-packed rallies — and the slow-moving admission lines — as opportunities to recruit new volunteers.

“That personal touch matters,” Becker said. “People really respond to it.”

While Clinton has held some public events in the state, such as a rally with 800 people at an Oakland school earlier this month, she’s not trying to match Sanders’ crowds.

“There are lots of ways to talk to voters, and all candidates do it in their own fashion,” Newman said. “Sanders’ strategy is big rallies ... but those rallies don’t always equal votes.”

Clinton courts core

Clinton’s team is focusing on getting her core supporters to the polls on election day.

While Sanders uses rallies and online outreach to gin up support, said Buffy Wicks, Clinton’s California campaign director, “we have already talked to 100,000 people (last) week” through a combination of online and in-person connections.

The campaign will push hard in cities with diverse populations — particularly Oakland, San Francisco, Los Angeles and throughout the Central Valley. Clinton’s people already are running phone banks and canvassing operations, not only in English but also in Cantonese, Mandarin, Vietnamese and Spanish.

“If you look at what her path to victory has been in the primaries — African Americans, Latinos, Asian-Pacific Islanders, women — that is her ultimate path to victory in the general,” Wicks said. “It’s building on the Obama coalition and making sure we can bring in this very diverse coalition of voters to the polls.”

But Clinton has to be cautious in her campaigning. Facing a progressive Democrat who already has shown an ability to bring young people and independent voters into the political system, she has to avoid slamming Sanders so hard that his hard-core supporters stay home in November.

“There’s no percentage in going on the attack against Bernie Sanders and his supporters,” Newman said. “We have to realize these are people who would vastly prefer President Clinton to President Trump.”

Crucial issues at stake

That doesn’t mean Clinton and Sanders won’t be battling on the issues.

The Clinton campaign is focusing on “economic proposals that are geared toward women and families,” Wicks said. That means the former senator from New York will be talking a lot about paid sick leave, equal pay for women, raising the minimum wage and her recently released child care proposal — issues the campaign believes will resonate with African American and Latino families.

Clinton will also push for tighter gun laws and hammer home that Sanders once voted to shield firearms manufacturers and sellers from some types of lawsuits. Former Rep. Gabby Giffords, D-Ariz., who was shot and badly wounded in a 2011 assassination attempt, will campaign for Clinton in California.

It’s an easier campaign plan for Sanders, who doesn’t have to worry about offending Clinton’s backers.

“Do not moan to me about Hillary Clinton’s problems,” Sanders said in an MSNBC interview this month, adding that he will “fight for every last vote I can get.”

Sanders’ advisers believe his policies — particularly on raising the minimum wage and free college tuition — are a natural fit in California, which Sanders repeatedly describes at campaign rallies as one of the country’s most progressive states.

While Clinton is in broad agreement with many of Sanders’ policies, she has taken a more cautious approach that doesn’t take political change nearly as far as the senator is demanding.

“It should be a very quick lesson to Democrats that we can do better in federal elections by being boldly progressive than by trying to kowtow to independents and Republicans,” said Ben Tulchin of San Francisco, Sanders’ national pollster.

Independent appeal

While Clinton is working to turn out traditional Democratic voters, Sanders’ success in California will depend on his ability to attract people who aren’t always part of the Democrats’ political playbook.

Much of Sanders’ effort is aimed at “two very important groups of voters that Hillary struggles with and that are going to be key in the general election — and that’s Millennials and independent men,” Tulchin said.

But that matters only if Sanders can make sure those occasional and “no party preference” voters show up at the polls and cast a Democratic ballot on June 7.

“There are potentially hundreds of thousands of independents ... who want to vote for Bernie Sanders,” but they will be out of luck if they don’t request a Democratic ballot, Tulchin said.

John Wildermuth and Joe Garofoli are San Francisco Chronicle staff writers. Email: jwildermuth@sfchronicle.com, jgarofoli@sfchronicle.com Twitter: jfwildermuth, @joegarofoli