Sen. John Kerry hasn't tried to make medical marijuana an issue in his presidential campaign, but he has some differences with President Bush on the subject.

Kerry says he would end the raids that have been a feature of the Bush administration's crackdown on medical marijuana in California, where voters approved the use of the drug for medical purposes in 1996. The Massachusetts senator has also signed a letter urging the administration to stop blocking medical marijuana research at the University of Massachusetts.

Perhaps most importantly, Kerry said at a campaign forum last year that his "disposition is personally favorable" to marijuana as medicine, but that he would await further scientific studies before taking a definitive stand. He also criticized mandatory minimum prison sentences for first offenders and called for more drug education and treatment.

That's not nearly as far as activists would like him to go. Kerry hasn't endorsed legalizing medical marijuana at the federal level or leaving the issue up to the states and hasn't backed legislation, currently stalled in Congress, that would allow patients and suppliers to use their state laws as a defense against federal charges.

But Kerry's position and tone suggest that he would take a different approach than Bush, who has escalated the federal war against state medical marijuana laws launched by his predecessor, Bill Clinton.

Where the Clinton administration focused on civil suits to shut down the nonprofit clubs that supplied marijuana to California patients, the Bush administration has used criminal prosecutions against growers and suppliers, has sent federal agents to seize a patient's six homegrown marijuana plants and is preparing for a high-stakes U.S. Supreme Court battle against two seriously ill Northern California women.

The president hasn't mentioned medical marijuana during the campaign. But in his last campaign, during a 1999 appearance in Seattle, he answered questions about the issue by saying, "I believe each state can choose that decision as they so choose.''

Bush, who regularly portrays his rival as a flip-flopper, has yet to explain his own apparent turnabout on this subject. Asked by The Chronicle about the president's views, now and in the past, Bush's campaign office reiterated his opposition to medical marijuana.

The issue may not have much effect on the presidential election. But the outcome of the election is likely to affect the future of medical marijuana, in part because of the case scheduled to be argued in the Supreme Court term that begins next month.

The two plaintiffs, Angel Raich of Oakland and Diane Monson of Oroville (Butte County), want court orders barring the federal government from interfering with their doctor-approved use of marijuana as therapy for their conditions, Raich's brain tumor and wasting syndrome and Monson's back spasms.

A federal appeals court ruled last December that the federal ban on marijuana couldn't be constitutionally applied to patients who obtain the drug without charge from within the state in which they live, if the state allows marijuana use for medical purposes. The ruling had the potential to shield local marijuana cooperatives from federal prosecution, but the Supreme Court granted the Bush administration's request to review the case.

If the government wins, it will be free to target patients as well as their suppliers in the nine states that have legalized medical marijuana. That decision would be up to the incoming administration, a circumstance that adds significance to Kerry's comments at an August 2003 town hall meeting in New Hampshire.

Asked by a local activist about marijuana, the senator said, according to a transcript, "My disposition is personally favorable but ... I want to get that scientific review to make certain that there's a way to manage it effectively. ... I certainly would put a moratorium on the raids until that has happened."

Kerry has said on other occasions that he would halt medical marijuana raids, sometimes specifying raids on patients. Dale Gieringer, California coordinator for the National Organization for the Reform of Marijuana Laws, says Kerry told him at a fund-raiser last year that he favored keeping federal agents out of medical marijuana clubs.

With regard to research, Kerry and his Massachusetts colleague, Sen. Edward Kennedy, signed a letter to the Drug Enforcement Administration last October urging approval of the University of Massachusetts' proposal to grow marijuana for its own federally approved medical research. When the DEA did not respond, researchers and advocates filed suit this July.

Kerry's campaign did not respond to requests from The Chronicle to spell out his position on medical marijuana.

Similar inquiries were made to the Bush campaign, including references to Bush's 1999 statement on leaving the issue to the states. The campaign's response didn't mention the 1999 comment, but instead accused Kerry of "flip- flopping on medical marijuana" by saying he was open to the issue but was withholding final judgment until research was completed. The campaign did not explain how those positions were inconsistent.

Bush's campaign also supplied a statement from then-press secretary Ari Fleischer at a 2001 press briefing. He said Bush "does not believe that it's appropriate to allow what is a controlled substance to be given to people in terms of medical marijuana. There are other effective ways, the president believes, to help people who suffer illness."