WASHINGTON - Senior Mexican government officials have lobbied U.S. leaders against legalizing marijuana in California, House Speaker Nancy Pelosi (who represents San Francisco) told HuffPost. The opposition to Proposition 19 further complicates what is already a disputed relationship between legalizing marijuana in the United States and reducing cartel violence in Mexico, much of which is fueled by the pot trade.

"I don't know if the state is ready to go that way," Pelosi said of legalizing pot in an interview in her Capitol office, "and I have the Mexicans coming in here and saying, 'Oh, my gosh, this is going to be problematic if in fact there's the decriminalization of marijuana." Mexican officials worry that legalization would lead to increased demand, which could funnel more money to the cartels. Backers of the initiative, however, note that under legalization, regulated production would take place within the state rather than in Mexico, cutting out the cartels.

Top Mexican leaders, meanwhile, including religious figures, have publicly called for a debate in Mexico about legalization, but the U.S. lobbying represents the most direct effort to influence American domestic policy on legalization. Both supporters and opponents of the proposition in the United States have pointed to a recent RAND study of the effect of legalization on the Mexican cartels. RAND, which is a largely government-funded operation, reported to the media that its study found there would be little effect on the cartels if Prop 19 passed. U.S. drug czar Gil Kerlikowske trumpeted the RAND study. "This report shows that despite the millions spent on marketing the idea, legalized marijuana won't reduce the revenue or violence generated by Mexican drug trafficking organizations," Kerlikowske told the AP. "The bottom line is that increased access and availability to marijuana jeopardizes the health and safety of our citizens."

Those statements to the press, however, belied the contents of the actual study.

"We believe that legalizing marijuana in California would effectively eliminate Mexican

DTOs'" -- drug-trafficking organizations' -- "revenues from supplying Mexican-grown marijuana to the California market. As we elaborate in this chapter, even with taxes, legally produced marijuana would likely cost no more than would illegal marijuana from Mexico and would cost less than half as much per unit of THC (Kilmer, Caulkins, Pacula, et al., 2010). Thus, the needs of the California market would be supplied by the new legal industry. While, in theory, some DTO employees might choose to work in the legal marijuana industry, they would not be able to generate unusual profits, nor be able to draw on talents that are particular to a criminal organization," concludes the report. It adds that if California goes on to export its pot crop to the rest of the country -- a likely scenario -- cartels could lose a fifth of their revenue.

In early October, Mexican President Felipe Calderon said in a speech that if California legalized marijuana, the United States would be committing gross hypocrisy by funding and encouraging a drug war south of the border while liberalizing laws on the north side that encourage drug consumption. "For me, it reflects a terrible inconsistency in government policies in the United States," said Calderon.

U.S. Attorney General Eric Holder has said that the federal government will continue to enforce pot laws in California if the proposition passes, setting up a federal-state conflict that could either advance the legalization debate or set it back. Medical marijuana has been legal in the state since 1996 and the federal government has only recently relaxed -- though not ended entirely -- enforcement of federal laws against medical marijuana patients.

Polling on Prop 19 has been all over the map, with recorded surveys finding higher support than live interviews, leading to speculation that voters are cautious about admitting their sympathies. On Tuesday, billionaire George Soros announced that he had given the cash-strapped Prop 19 campaign a million dollar contribution. The measure is estimated to raise $1.4 billion in revenue annually.

Pelosi wouldn't say how she'll vote on Tuesday on Prop 19, but appeared open to supporting it. "In terms of marijuana, I have always been for medicinal use of marijuana for a very long time. I think we pretty much have crossed that bridge. I hope so anyway. It seems unfortunate that it had to be such a struggle, when it was so self-evident that it was effective. I'm pleased with the bill that Gov. Schwarzenegger signed to take it from a misdemeanor to an infraction, so our law enforcement people are not consumed in issues that relate to personal use," she said when asked about Prop 19. "I haven't taken a position on the [proposition], but I like the steps that have taken us in a direction where we can look in a more clear-headed way and less-emotional way about where we should go in this."

Pressed by HuffPost to answer the question as if a pollster had called her and asked which way she was leaning, she demurred. "But you're not a pollster," she noted.

Ryan Grim is the author of This Is Your Country On Drugs: The Secret History of Getting High in America