SACRAMENTO — California will open vacant state land to emergency shelters for homeless people under an executive order that Gov. Gavin Newsom intends to sign Wednesday.

The order, which Newsom announced ahead of his annual budget plan due this week, would also create a fund to pay rent and build affordable housing for homeless people. The governor will propose to start the fund with $750 million in taxpayer money, which the Legislature would have to approve.

With the homeless population surging by double-digit percentages in many cities across the state, and California coming under fire from President Trump for its widespread encampments, Newsom is under increasing pressure to get people off the streets. Homelessness has become the biggest issue of concern to Californians, recent polls show.

Newsom’s executive order will create a state system to track how well local governments are doing in moving homeless people from the street to more stable living situations, according to a summary provided by the governor’s office.

Newsom said in a statement that the order aims to directly connect homeless people with emergency housing and treatment programs.

“Californians have lots of compassion for those among us who are living without shelter,” he said. “But we also know what compassion isn’t. Compassion isn’t allowing a person suffering a severe psychotic break or from a lethal substance abuse addiction to literally drift towards death on our streets and sidewalks.”

The order instructs four state agencies to identify properties that could be made available for short-term homeless shelters. The properties include excess state land that has been set aside for affordable-housing development, lots next to highways and state roads, decommissioned hospitals and health care centers, and fairgrounds.

It will also provide cities and counties with 100 travel trailers from a state fleet and tent structures to set up temporary housing and health and social services. Details about the timeline and eligibility criteria were not included in the summary of the executive order.

There is ample precedent for using excess government land for homeless programs, starting with a 1987 law that allows the leasing of surplus federal property for homeless services for free. And over the past two years, San Francisco has put two Navigation Center shelters on underused Caltrans property on Fifth Street and in the Bayview, at virtually no cost for the land.

Although the governor’s order creates the new fund to support housing access for homeless people, which could also include board-and-care homes for the mentally ill, any state appropriation would require the Legislature’s approval as part of the budget process. Lawmakers will not approve a spending plan until June. In the meantime, Newsom said he will seek contributions to the fund from the private sector and philanthropies.

As part of his 2020-21 budget plan, Newsom will also propose expanding Medi-Cal, the state’s health care program for the poor, to include preventive care and housing support services that could keep chronically homeless people out of the emergency room and other costly care. With matching federal money, the expansion would cost $1.4 billion a year.

Other new initiatives in Newsom’s budget proposal include a task force to redesign mental health services for homeless people and a study of the root causes of homelessness in California.

Newsom entered office a year ago promising a greater focus on combatting California’s homelessness crisis, including by appointing a statewide homelessness czar to lead the state’s response.

In his first year, he gave cities and counties $650 million in emergency aid to fight homelessness and signed laws to speed up shelter construction by granting exemptions to environmental regulations and eliminating the public’s ability to challenge the approval of Navigation Centers that meet local zoning requirements.

But his czar never materialized. In August, Newsom said he would rely instead on the advice of a task force he appointed to explore strategies for addressing homelessness.

The panel has been looking into possibilities including mandating shelter or housing for street people, and Newsom credited it for inspiring many of the ideas in his order. But several members have long said that their understanding is that whatever they come up with, Newsom will follow his gut.

“Gavin is the homeless czar in California. Period. End of story,” said Philip Mangano, who is on the task force and was national homeless czar as head of the U.S. Interagency Council on Homelessness under Presidents George W. Bush and Barack Obama. “He will own this issue and do the right things — not the task force.

“He is a businessman, and he is smart enough to want some R&D, so he appointed the task force. And that is what we are doing. We are bringing research and development to the governor, and he will act.”

Mangano worked closely with Newsom when he was San Francisco mayor to steer the city’s emphasis more toward supportive housing than shelter, and the effort dramatically reduced the street counts for several years in the mid-2000s before they began climbing again. The city’s homeless population was up 17% over the past two years in the most recent count.

Statewide, homelessness has also shot up in recent years, despite billions of dollars being approved by voters up and down California for supportive and affordable-housing programs. The latest count taken in 2019 found 151,278 homeless people in the state, an increase of 16% since 2018.

Alexei Koseff and Kevin Fagan are San Francisco Chronicle staff writers. Email: alexei.koseff@sfchronicle.com, kfagan@sfchronicle.com Twitter: @akoseff, @KevinChron