A controversial proposal to build a billionaire-backed city in California is trying to win over locals with a package of lavish benefits – including $400 million in “down payment assistance” for homebuyers and a guarantee of 15,000 new jobs.

As The Post has reported, California Forever — the firm behind nearly $1 billion in secretive land purchases in Solano County northeast of San Francisco — has faced major blowback from residents and federal lawmakers alike ahead of the November vote that will decide if the project can move forward.

California Forever said the $400 million in financial assistance would provide a pathway for local Solano County residents, including “working families, teachers, nurses, police and firefighters, and construction workers,” to own property in the new development, according to its website.

Officials also insisted that the city would support at least 15,000 jobs that would “pay at least 125% of county average weekly wage by the time we hit 50,000 residents.” The median household income in Solano County was $97,037 as of 2022, according to US Census data.

“This can be a new economic engine for Solano County,” said California Forever CEO Jan Sramek, who is set to take questions about the ballot proposal from local residents at a press conference on Wednesday afternoon.

The bold promises are part of a list of a so-called “ten guarantees” that the project’s executives say they will provide if their ballot passes. California Forever said the pledges would be “legally binding and enforceable by the county,” though it wasn’t immediately clear how that mechanism would work.

Other pledges include $200 million to revitalize neighboring cities such as Fairfield and Rio Vista; $70 million in earmarks for scholarships, vocational training and small business support and $30 million toward the protection of the local environment.

The firm said its development would primarily consist of row houses and apartment buildings and be built on approximately 18,600 acres of land – a fraction of the roughly 62,000 acres it has acquired while becoming Solano County’s largest landowner since 2017.

The city plan would also require that at least 4,000 acres be used for environmentally friendly uses such as parks, trails and community gardens.

California Forever has yet to say what the city would be named if construction were to move forward.

Silicon Valley titans, including Marc Andreesen, Reid Hoffman and Laurene Powell Jobs, are bankrolling the project, which critics have blasted as a ruthless land grab that will force out locals and damage fragile ecosystems.

Sramek – a Czech-born Goldman Sachs trader who was recently compared to a “snake-oil salesman” by wary residents – has billed the city plan as an answer to the state’s skyrocketing housing costs and brutal commutes.

He has rejected rampant speculation that his deep-pocketed backers want the city to fit their ideals of a “utopian” community.

Residents need to sign off in order for California Forever to bypass Solano County rules blocking re-zonings without voter approval.

US Rep. John Garamendi (D-Calif.), who previously accused the project’s bosses of using “strong-arm mobster techniques” against local landowners who opposed their plans, remains unconvinced by the proposal.

During a meeting on Capitol Hill last week, an outraged Garamendi told Sramek that he was “despicable” for refusing to drop a $515 million lawsuit accusing local landowners of engaging in a collusive price-fixing scheme to extract more money for their property, Bloomberg reported.

Garamendi’s office did not immediately return a request for comment.

Despite the blowback, Sramek recently told The Post that his billionaire backers are “not at all” perturbed by the negative press.

The ballot proposal is just one remaining hurdle for California Forever.

The project also faces a lingering national security probe by the US Treasury Department’s Committee on Foreign Investment in the United States over potential foreign ties to its land-buying deals.

Garamendi and other lawmakers have demanded close scrutiny because much of the land acquired by California Forever through its subsidiary Flannery Associates is located near Travis Air Force Base, a crucial military hub.

California Forever said its development plans would nearly double the land barrier outside Travis from about 8,000 acres to nearly 15,000 acres. The group also pledged to work with base leaders on any “key infrastructure projects,” including planned solar farms in the area.