White House hopefuls in both parties are taking donations from people in the new marijuana industry, which is investing heavily in political activism as a route to expanded legalization and landed its first major candidate, Rand Paul, at a trade show last month.
Several Republicans, like Democrats, are saying they won't interfere with states that are legalizing a drug still forbidden under federal law. And at conservative policy gatherings, Republicans are discussing whether drug sentences should be eased.
A quarter century after Bill Clinton confessed he tried marijuana but insisted "I didn't inhale," the taboo against marijuana is shrinking at the highest level of politics, just as it appears to be with the public.
"When I was growing up, it was political suicide for a candidate to talk about pot being legal," said Tim Cullen, owner of Colorado Harvest Co., a chain of medical and recreational marijuana dispensaries.
Cullen attended a Hillary Rodham Clinton fundraiser in New Mexico last month and talked to the Democratic candidate about her position on legalizing pot.
"She's not outwardly hostile to the idea, which is a big step forward," Cullen said. "She's willing to openly talk about it at least."
A slim majority of Americans, 53 per cent, said in a Pew Research Center survey in March that the drug should be legal. As recently as 2006, less than a third supported marijuana legalization in another measure of public opinion, the General Social Survey.
Politicians are shifting, but slowly.
Republican candidates Jeb Bush, Ted Cruz and Rick Perry are among those who say states should decide marijuana laws, even as they brand legalization a bad idea. In June, Paul became the first major-party presidential candidate to hold a fundraiser with the new marijuana industry, courting about 40 donors in Denver.
But the Kentucky senator used a private back door, and aides erected a screen so photographers couldn't see the candidate standing by a green Cannabis Business Summit sign. Paul didn't talk about pot at a public meet-and-greet afterward.
A few days earlier in the same building, six other GOP presidential contenders talked to about 4,000 people at a gathering of Western conservatives. There, Perry defended the right of states to change marijuana laws, even if they "foul it up."
"Colorado comes to mind," the former Texas governor said, to laughs and applause. "I defend the right of Colorado to be wrong on that issue."
Altogether, 23 states and the District of Columbia are flouting federal law by allowing marijuana use for medical or recreational purposes.
Not all candidates say leave it to the states. New Jersey Gov. Chris Christie and former Pennsylvania Sen. Rick Santorum say they would fight to roll back marijuana legalization efforts in states such as Colorado.
Democrats are generally less critical of states legalizing pot, but they're treading carefully, too.
Clinton said last year that more research needed to be done on marijuana's medical value, but "there should be availability under appropriate circumstances." She didn't elaborate what those circumstances should be.
As for her main Democratic rival, Vermont Sen. Bernie Sanders sounds lukewarm about legalization, despite his counterculture roots and liberal social views. He told Yahoo News that pot should be decriminalized but he was not ready to go beyond that. He said he smoked pot twice in the old days and "coughed a lot."
Bush and Cruz have also acknowledged using marijuana in their youth, as has President Barack Obama.
Marijuana entrepreneurs say even tepid support for legalization is a step forward, and they're opening their wallets in hopes of seeing more change.
The largest marijuana lobbying group, Marijuana Policy Project, plans to donate tens of thousands to 2016 presidential candidates. Executive Director Rob Kampia was among those at the Denver pot fundraiser.
"We wouldn't have heard a presidential candidate talking that way four years ago," Kampia said. Attendees said Paul talked about changing federal drug-sentencing laws but stopped short of calling for nationwide legalization.
It's unclear how much money the marijuana industry will spend on the presidential race. Many pot-business owners don't list their businesses on campaign-finance disclosure forms, given the drug's federal illegality. And some marijuana activists are likely to spend not on the presidential contest but on campaigns in the six to 10 states likely to have some sort of marijuana policy on ballots next year.
Still, the presidential race appears certain to include more talk of marijuana policy than before.
"There are a lot of loose bricks in the walls of resistance to changing drug laws in America," said William Martin, who studies drug policy at Rice University. "It's no longer a silly question, legalizing marijuana."
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