A stricter set of rules and a surprise political alliance are helping build momentum for a long-thwarted effort to legalize marijuana for medical purposes in Illinois.

Some lawmakers are looking to make cannabis available for people seeking relief from symptoms of maladies that include multiple sclerosis, cancer and HIV/AIDS.

To pick up support, they must allay fears by opponents concerned that the measure is the first step toward decriminalizing marijuana and worried that Illinois will end up likeCalifornia, where pot is easily available to anyone with a doctor’s note and complaints about headaches or anxiety.

In Illinois, doses would be dispensed from a limited number of highly regulated not-for-profits, rather than drugstores. Penalties including potential prison time would discourage attempts to turn a medical prescription into dime bags on the street.

In January, the issue fell four votes shy during a lame-duck session where lawmakers approved such controversial measures as a major income-tax increase, civil unions for same-sex couples and a death penalty abolition.

This time, House Republican Leader Tom Cross has dropped his opposition. He came on board after being approached by several constituents who pressed him to allow marijuana use for “”the worst-of-the-worst medical conditions,”” a spokeswoman said.

Sponsoring Rep. Lou Lang, D-Skokie, who has championed the issue for three years, said he thinks he can finally pass a medical marijuana bill out of the House. The Senateapproved a less restrictive version last year.

Whatever the final form, an Illinois law can’t come too soon for residents who now use medical marijuana illegally. Julie Falco said she’s been using cannabis since 2004 to manage symptoms of multiple sclerosis.

Falco said she felt she had no other choice because prescription drugs left her feeling lethargic and depressed and came with side effects such as hearing loss.

“”I was contemplating taking my own life,”” said Falco, who lives on the Far North Side. “”I didn’t have any hope.””

Scientists and physicians say medical research has shown scant evidence that marijuana is a safe and effective treatment for many of the afflictions the Illinois bill would cover.

A handful of uses in the bill — like pain suffered by people with AIDS and cancer — are supported by some solid scientific evidence. But none meets the standards, such as large, well-designed clinical trials, required by the U.S. Food and Drug Administration in approving new drugs.

Fifteen states, including Michigan, have legalized medical marijuana. The sponsors of Illinois’ bill are trying to make it the most restrictive in the nation.

Those with a prescription would not be allowed to grow their own marijuana but would have to buy it from a state-licensed dispensary. The bill would limit the number of outlets to 59 — one per Senate district.

The latest version would legalize medical marijuana for three years, then lawmakers would review how it went. Democratic Sen. Bill Haine, a former state’s attorney in Madison County, said the new safeguards should help the legislation gain support.

“”Many people just flat don’t accept that marijuana can do any good, but it’s a natural substance that can be good, just as many prescription drugs are good for some uses and not for others,”” Haine said.

For Cross, the House GOP leader from Oswego, supporting the measure represents a change from January, when he voted against the idea.

Cross, who has a child with diabetes, sponsored a law that ensures researchers could work with embryonic stem cells in Illinois.

“”I’ve seen him evolve on this thing,”” said Rep. Angelo “”Skip”” Saviano, R-Elmwood Park. “”It fits his philosophy on not limiting tools to the medical community to treat these diseases.””

Saviano has long supported legalizing marijuana for medical use. He watched his father die of cancer in 2001 after suffering side effects of chemotherapy. Saviano said he believed that marijuana could have helped reduce his father’s nausea and increase his appetite at a time when he lost a lot of weight.

Supporters can’t exhale yet. The lame-duck lawmakers are no longer in office and the measure needs to pass the House, Senate and be signed by Gov. Pat Quinn if it’s to become law.

Rep. Jim Durkin, R-Western Springs, said this is not an issue Cross or Republican leadership will “”twist arms”” on to get support. Durkin, a former prosecutor, voted “”no”” in January but said he is keeping an open mind on the new version.

A law has been on the books since the late 1970s allowing doctors to prescribe marijuana in pill or plant form to treat glaucoma, the side effects of chemotherapy or radiation therapy for cancer patients or other procedures deemed medical necessities. But the physician must get authorization from the Department of Human Services and written approval from the state police.

A state human services spokeswoman and a state medical society representative say they’re not aware that any doctor has ever asked permission to prescribe marijuana in Illinois.

Lang, the House sponsor, said he’s aware of the existing law but argues his proposal is a tighter and more workable measure.

“”What we have done is take the best ideas on the topic from America and in Illinois during debate to gauge the tolerance of colleagues and make the best and tightest bill in the country,”” Lang said.