LOS ANGELES – Fourteen years after California decided marijuana could be used as a medicine and ignited a national movement, the state is likely to vote on whether to take a decisive step into the vanguard of drug liberalization: legalizing the controversial weed for fun and profit.

Today, Los Angeles elections officials must turn in their count of valid signatures collected in the county on a statewide legalization initiative. The number is virtually certain to be enough to qualify the initiative for the November ballot, according to a tally by state election officials.

That will once again make California the focal point of the long-stewing argument over marijuana legalization, a debate likely to be a high-dollar brawl between adversaries who believe it could launch or stifle another national trend.

The campaign will air issues that have changed little over the years. Proponents will cite the financial and social cost of enforcing pot prohibition and argue that marijuana is not as dangerous and addictive as tobacco or alcohol. Opponents will key on marijuana-linked crimes, rising teenage use and the harm it causes some smokers.

But the debate also will play out against a cultural landscape that has changed substantially, with marijuana moving from dark street corners to neon-lit suburban boutiques. In the months since the Obama administration ordered drug agents to lay off dispensaries, hundreds have opened, putting pot within easy reach of most Californians. Whether voters view this de facto legalization with trepidation or equanimity could shape the outcome.

The measure’s supporters hope this dynamic will shift the debate, allowing them to convince voters to replace prohibition with controlled sales that could be taxed to help California’s cities and counties. “They already accept that it’s out there. They want to see a smart strategy,” said Chris Lehane, a top strategist for the legalization campaign.