The backbreaking work in California’s chili pepper fields and cherry orchards wasn’t so noticeable when farmworker Antolin Gonzalez was young. But the 49-year-old south Santa Clara County farmworker now suffers from dizziness, allergies from dust and pesticides, swollen feet and throbbing backaches — even eyesight problems from prolonged exposure to ultraviolet light.

Like many of the state’s 2.5 million illegal immigrants, Gonzalez does not have health insurance because he can’t afford it. If he gets sick, he seeks treatment at a public health clinic. Anything more serious means a trip to the hospital emergency room.

But on Monday, state legislation that would extend free or low-cost health care coverage to immigrants who are in the country illegally heads to the Senate Appropriations Committee for a key vote.

If Senate Bill 4 can make it over that hurdle, through the Assembly and ultimately garner Gov. Jerry Brown’s signature, more than a million low-paid undocumented farm and construction workers, hotel maids and service workers would qualify for Medi-Cal, the state’s health program for the poor.

Furious opponents, however, say it’s just another example of liberal legislators opening up California’s wallet — to the world.

Authored by Sen. Ricardo Lara, D-Bell Gardens, SB 4 is a second crack at a similar bill he proposed last year. That measure stalled in the appropriations committee because of its $1.3 billion price tag.

But Lara argues that the current bill is altered in ways he believes will significantly reduce costs. One key difference is that his first bill would have required Covered California, the state’s health insurance exchange established under the Affordable Care Act, to offer subsidized health care coverage for undocumented Californians through a separate exchange.

A fiscal analysis of SB 4 obtained by this newspaper before its scheduled release to the public on Monday shows that annual Medi-Cal costs for covering the undocumented would range from $175 million to $740 million, depending on whether President Barack Obama’s executive order giving nearly 5 million illegal immigrants protection against deportation takes effect. The order, issued late last year, remains blocked — at least temporarily — in federal court.

If the order is eventually upheld in court, about 900,000 of California’s undocumented immigrants would become eligible for Medi-Cal without Lara’s bill, the legislative fiscal analysis says.

In addition to expanding Medi-Cal to illegal immigrants, SB 4 would also allow illegal immigrants with higher income levels to use their own money to buy an unsubsidized private health plan through Covered California. Unlike traditional Medi-Cal costs, which are split between the state and federal government, California would be on the hook for the entire tab. The state also would need a waiver from the federal government to allow it to sell private plans on the exchange to illegal immigrants.

The bill’s proponents seem confident it will become law.

“Californians have shown themselves to be very supportive of the immigrant community,” said Reshma Shamasunder, executive director of the California Immigrant Policy Center, a nonprofit group that advocates pro-immigrant policies.

She cites as examples a California law that offers in-state tuition to illegal immigrants, as well as a new law that allows them to get driver’s licenses.

Shamasunder calls the bill a “modest investment for a huge return,” noting that one study estimates it would cost pennies on each dollar that California spends on Medi-Cal, which now covers nearly 1 in 3 Californians.

But critics say the bill places another burden on taxpayers already overwhelmed by the costs of illegal immigration.

“A health care bill would certainly incentivize more illegal immigrants to come here, and that is something that California at this point does not need,” said Joe Guzzardi, spokesman for Californians For Population Stabilization in Santa Barbara.

“We’ve got lots of problems to solve — some are overwhelming, like the drought,” Guzzardi said. “More legislation for immigrants would just put more strain on the state.”

At the Institute of Governmental Studies at UC Berkeley, political science professor Jack Citrin remains skeptical about the bill’s chances.

Even if the Legislature passes it, he said, the bill stands a good chance of being vetoed by the governor, who “is not particularly sympathetic” to adding permanent costs to the state budget.

Moreover, Citrin doubts the Obama administration would modify the current terms of the Affordable Care Act to benefit illegal immigrants, especially after the backlash from congressional Republicans after he signed the executive order aimed at halting deportations.

Like many Santa Clara County farmworkers, Gonzalez knows about Obama’s immigration order. But he’d never heard of Lara’s bill, something he said he’d welcome.

“That sounds pretty good,” Gonzalez said.

For now, he often receives medical care from county doctors and nurses who staff a mobile medical clinic that visits local farms once a week in the evenings.

Inside a patient room at the back of the bus, Gonzalez was recently seen by Dr. Ari Kriegsman, who treated another half-dozen farmworkers that night.

Called Saludos, the clinic is part of a county program that provides comprehensive health care services to the valley’s homeless population, which extends to farmworkers as well.

It shares a similar goal with SB 4.

“Providing care to those least able to afford or access care is both the right and smart thing to do,” said Dr. Sara Doorley, the program’s medical director. “By preventing illness in our community, we help to keep all residents healthy and safe.”

Contact Tracy Seipel at tseipel@mercurynews.com or 408-920-5343 and follow her at Twitter.com/taseipel.