SACRAMENTO — Riding the strength of surging tax revenues, Gov. Gavin Newsom proposed a revised $213 billion state budget Thursday that is $4 billion higher than his initial plan in January.

But Newsom would set aside nearly half the additional money for paying down debts and for building reserves, potentially setting up a showdown with liberal lawmakers who have pushed for greater spending on health care, early childhood education and social services.

Like his predecessor, former Gov. Jerry Brown, Newsom warned that the state needs to be ready for the next economic downturn.

“We are preparing for a very different climate,” he said, “and we’ve never been more prepared as a state for entering into that climate.”

His budget plan, which forecasts a surplus of $21.5 billion, largely prioritizes one-time spending over new programs that would continue indefinitely. Notable exceptions include Newsom’s earlier proposals to offer a second year of free tuition for community college students and to expand Medi-Cal, the state’s health coverage for the poor, to undocumented young adults.

After a March meeting with the mayors of California’s biggest cities, Newsom also revamped his approach to tackling the state’s housing and homelessness crises.

His revised proposal would move $500 million to a program that funds infrastructure projects such as sewer hookups and sidewalks for new affordable housing, instead of handing it out as rewards for cities and counties that hit housing construction targets.

Newsom proposed adding $300 million to his January funding plan for homelessness programs. The new money would pay for more mental health professionals, housing for university students and legal aid for tenants facing eviction.

Half it would go toward homeless aid programs run by cities and counties, which were previously set to receive $500 million. That would make $650 million available next year to build emergency shelters, convert hotels and motels to housing, or launch navigation centers like those pioneered by San Francisco.

The mayors with whom Newsom met in March told him that $500 million provided in this year’s budget had quickly run out.

“Look, this homeless issue is out of control,” the governor said at a Sacramento news conference Thursday. “It is a stain on the state of California.”

Newsom, who was elected with strong support from California’s powerful teachers unions, emphasized that his budget plan would designate far more for K-12 education than is constitutionally required under Proposition 98, the school-funding initiative approved by voters in 1988. Previous governors, he said, have treated that minimum like a ceiling.

His revised proposal includes a nearly $700 million increase for special education funding, about $120 million more than he suggested in his initial budget in January. It would also redirect about $150 million to teacher training and paying off loans for newly credentialed teachers who agree to work in schools with high turnover. The money had originally been set aside to help California expand full-day kindergarten to every school district.

Other proposed new spending includes $75 million to shore up the response to an expected increase in power shutoffs by utilities worried about sparking wildfires, and $71 million to launch a redesigned substance abuse program in California prisons, where drug overdoses are climbing.

Newsom had already previewed on Tuesday a budget plan to benefit working families. His revised proposal would repeal sales taxes on diapers and menstrual products, a longtime priority of female lawmakers, though Newsom revealed Thursday that the repeal would expire after two years unless the Legislature renewed it.

The proposal would also provide new parents with two additional weeks of paid leave, bringing the total to as much as four months per baby. The governor has said he eventually wants to extend that to six months.

The revised budget proposal received a warm response Thursday from legislative leaders. But booming tax receipts portend challenges for Newsom with the Legislature, which must send a budget to the governor by June 15.

Lawmakers, most of whom are now Democrats, have their own suite of big-dollar ideas that must be reconciled with Newsom’s. They include a broader push to make Medi-Cal available to all undocumented immigrants, regardless of age.

Assembly Democrats have floated a more aggressive outline to reach universal preschool than Newsom, who backed away Thursday from a January proposal to enroll all 4-year-olds from low-income families in state-subsidized child care over the next three years.

Assemblyman Phil Ting, the San Francisco Democrat who chairs the Assembly Budget Committee, said Newsom’s plan reflects the priorities of the Legislature, but they would haggle over the details in the weeks ahead and “how much can be done within the limitations of the budget.”

A bigger challenge may be resistance to several new taxes Newsom has built into his budget plan.

These include a monthly surcharge on water users to assist communities without clean drinking water, a fee on phone bills to update the state’s 911 system and an individual mandate to buy health insurance, which would carry a penalty that could fund insurance subsidies. Newsom also wants to make changes to the business tax code to pay for an expansion of California’s tax credit for the working poor.

Although Democrats hold more than a two-thirds supermajority in both houses, which would allow them to raise taxes without any Republican votes, members from swing districts can point to Josh Newman as evidence that their constituents may be hostile to new taxes. Newman, a Democratic state senator narrowly elected in Orange County in 2016, was recalled last year after he voted to increase the state’s gas tax to pay for highway and transit improvements.

“I tell them nothing,” Newsom said of lawmakers hesitant to vote for the taxes. “I tell them, ‘Do the right thing. Do what will make you proud.’”

Alexei Koseff is a San Francisco Chronicle staff writer. Email: alexei.koseff@sfchronicle.com Twitter: @akoseff