Alaska and Oregon may become the next states to legalize marijuana for recreational use, as early as next year some proponents say.

Following President Barack Obama’s August decision to relegate marijuana prohibition to the state level as Colorado and Washington voters approved legalization, marijuana reform activists intend to pursue a state-by-state strategy. Such a strategy is similar to treatment of other contentious issues, such as abortion, gun control, and the death penalty.

But the big battle over marijuana prohibition will come in 2016 with the next presidential election, when proponents of marijuana legalization say younger voters will visit the polls in greater numbers. Although a slim majority of Americans support legalization, younger voters may vote for change in higher numbers than older generations, Mason Tvert, a spokesman for the Marijuana Policy Project, says.

That group, and others, plan to target state legislators in five states, including Rhode Island and Hawaii, to legalize the drug by 2017. Presently, the U.S. government classifies marijuana as a Schedule II controlled substance with no redeemable medical use, in accordance with international standards held by the United Nations (UN).

Beau Kilmer, co-director of the RAND Drug Policy Research Center, told Reuters that marijuana legalization proponents would try to get the issue on state ballots by next year. "I wouldn't be surprised to see legalization on the ballot in Alaska and Oregon in 2014," Kilmer said. "I expect the groups trying to put it on the ballot in these states to learn from what has happened in Colorado and Washington State."

Those two states became the first in the nation to legalize marijuana for recreational use among adults following approval by voters last year on state ballots. Presently, 20 states and the District of Columbia allow marijuana for medical treatments, while nearly half of U.S. states have decriminalized marijuana. This summer, Vermont became the latest state to reduce the possession of small amounts of marijuana a civil infraction, and may soon become a battleground state for legalization following democratic Gov. Peter Shumlin’s overture last month to “discuss” the issue.

An evolving political climate has emboldened marijuana legalization activists such as Anthony Johnson, director of New Approach Oregon, one of a two such campaigns in the state. “Originally I agreed with the Marijuana Policy Project and other activists who urged waiting until 2017," he told Reuters. “But I've been convinced there's a path to victory in 2014."

UN drug control officials remain alarmed by challenges to marijuana prohibition in America, Germany, and Uruguay.