DENVER – Once a politically dangerous subject, legal marijuana has become something of a de facto platform plank for the 2020 Democratic candidates: All support either legalizing or decriminalizing its use, and the differences lie in how far the candidates are willing to take it.

Those differences – particularly former Vice President Joe Biden's reluctance to embrace full federal legalization and the lack of enthusiasm that increasingly organized young marijuana activists have for him – may play a role in determining who faces President Donald Trump next fall, experts said.

“People from both parties are just thinking, ‘Duh, we should be legalizing this at the federal level,’ ” said Rachel Gillette, a Denver-based cannabis activist and attorney. “It would be great if they could focus on this. It’s time.”

Democratic presidential candidates Sens. Cory Booker, Bernie Sanders, Kamala Harris, Elizabeth Warren and Michael Bennet are all co-sponsors of a Senate proposal that would make marijuana legal, expunge criminal records and create a reinvestment fund to aid communities hurt by the war on drugs.

“The debate has changed dramatically in the past couple years. It’s very new. It’s very new, and it’s very welcome," said Andy Bernstein of HeadCount, a voter registration nonprofit group targeting concertgoers and cannabis users. "A decade ago, mentioning marijuana made you a fringe candidate. Today, you’re out of the mainstream if you don’t have a position, and a position to provide greater access.”

The 2020 election is a far cry from the 2016 race, when Sanders was the only major-party candidate to call for legalization. Relentless behind-the-scenes lobbying helped shift the conversation among Democrats during this election cycle, when 65% of Americans said medical marijuana should be available to adults, according to a CBS News poll in April.

The poll highlighted a major demographic split: 49% of people 65 and older supported legalization; the number jumped to 72% for people ages 18-34. The poll found that 56% of Republicans supported legalization compared with 72% of Democrats.

In the 2016 presidential election, about 66% of eligible voters age 30 and above cast ballots, compared with 50% of eligible voters ages 18-29, according to the nonpartisan Nonprofit VOTE and the U.S. Elections Project.

"We think this is the biggest opportunity to turn out people who otherwise don’t vote," Bernstein said. "This could be the thing that brings those people out and makes nonvoters into voters.”

Kyle Kondik, managing editor of Sabato’s Crystal Ball at the University of Virginia Center for Politics, said that although younger voters might be more interested in a candidate with a strong legalization platform, the overall trend across the country favors legalization. The candidates' broad support for marijuana law changes suggests that primary voters might look elsewhere for significant distinctions, Kondik said.

For many activists, the conversation has swept past whether people should be allowed to smoke pot and is more often focused on how hard the federal government should work to mitigate the impact of the war on drugs, which for generations has disproportionately hurt minority communities.

"Supporting legalization is no longer enough," said Queen Adesuyi, 25, national affairs policy coordinator for Drug Policy Action, the political advocacy arm of the nonpartisan Drug Policy Alliance. "There's a large segment of the public that purely cares about marijuana. And then there's other people who come to the table principled by the concept that mass incarceration is destroying lives and destroying communities."

South Bend, Indiana, Mayor Pete Buttigieg and Biden represent gradations in the party's approach to marijuana. On Aug. 23, Buttigieg called for decriminalizing all drugs. Biden seeks to remove marijuana as a Schedule 1 controlled substance, then let states decide whether to legalize it, an expansion of the de facto Trump policy, which is to leave alone states with legal pot, while moving toward greater research access.

Biden's plan calls for expunging marijuana-related criminal records but stops short of using federal resources to help communities of color launch canna-businesses via "social equity" programs. In Illinois, the most recent state to legalize recreational marijuana, the state's system was specifically designed to help minorities open cannabis stores, establishing a new tax base and creating potentially thousands of jobs.

Adesuyi of Drug Policy Action said Biden's reluctance to endorse full legalization is a legacy of his role in creating and funding the war on drugs during his lengthy Senate career that began in 1973 and included stints as chairman of the Judiciary Committee.

Especially for young voters, she said, a candidate's attitude toward marijuana is a proxy for a wide array of issues, including "social justice" and criminal justice changes.

That might hurt Biden's chances in the early primaries in March 2020, which include large sections of the South, along with California.

"Biden has been unapologetic for where we are in this country over prohibition. He is so far behind the tide it's embarrassing," Adesuyi said. "What Biden is proposing is garbage. His position on this is intended to mitigate the fact that he is a drug warrior."

Buttigieg dubbed his efforts to link criminal justice changes and marijuana legalization the "Douglass Plan," which includes sweeping changes to educational, health care and economic development systems and is aimed at lifting African American communities. Buttigieg's plan is named after Frederick Douglass, a former slave who became a famous abolitionist and newspaper owner.

Skyler McKinley, a Colorado-based Democratic political activist who helped write the state's first-in-the-nation marijuana rules, said he doesn't think Biden's stance will cost him large numbers of voters. That's because 11 states and Washington, D.C., legalized without federal interference, aided by the power of the 10th Amendment, which grants states' rights.

“I don’t think this is a top issue for any voter, because under Obama and now Trump, states can experiment with legalization themselves," he said. "If you’re running for governor of a state, this can be a major thing. But running for president, you’re either in support of the 10th Amendment or you’re not.”

Because the first primaries and caucuses take place in Iowa and New Hampshire, which are traditionally more conservative, Biden's approach might boost him there, giving him momentum going into the later contests.

Politicians make those kinds of calculations every day, said Tom Daschle, former Senate majority leader and South Dakota Democrat who joined the advisory board of Northern Swan Holdings, a multinational cannabis company.

"I think that debate is only going to get louder and more pervasive as time goes on," said Daschle, who described himself as an "incrementalist" when it comes to marijuana legalization.

Daschle said politicians of his generation, including Biden, generally favor a slower approach, such as decriminalization and rescheduling, along with criminal justice changes.

He said Democratic candidates might be better served by talking more about the potential economic impacts of legalizing or rescheduling cannabis, from job creation to the impact on real estate prices and even the taxes marijuana businesses pay. That would be in addition to, not instead of, discussion of the social and criminal justice issues, he said.

"There's enormous support for limited use of cannabis already, and I think there's little doubt that as younger generations take leadership roles in government and business and life, we're going to see a more rapidly evolving attitude on cannabis," Daschle said. "If you're just looking at the politics of this, what does this do in the general election? Well, you may win over this angry young activist, and then you can't win over the people who are not willing to go so far, so fast."