The so-called Proposition 19 -- one of a series of referendums held at the same time as mid-term polls -- were rejected by 57 percent against 43 percent in favor, said CNN, while Fox News and the LA Times also forecast a No vote.

Growing and selling marijuana for medicinal purposes has been legal here since 1996, but backers of legalizing it totally -- including consumption, cultivation and trade -- campaigned hard for "Prop 19" to be passed.

The proposal would have allowed people aged 21 and over to possess up to one ounce (28 grams) of marijuana and grow up to 25 square feet (2.32 square meter) of pot plants.

Supporters of the measure -- which drew widespread backing among the young, but opposition from older voters -- sought to put a brave face on the ballot defeat.

"The fact that millions of Californians voted to legalize marijuana is a tremendous victory," said Richard Lee, proponent of the referendum proposal, adding that he would mount a similar bid two years from now.

"We have broken the glass ceiling. Prop. 19 has changed the terms of the debate and that was a major strategic goal."

"With limited resources this time around we were able to build an enormously powerful coalition.... This coalition will only continue to grow in size and strength as we prepare for 2012."

Large-scale commercial cultivation -- and its taxation -- could also have been allowed, though implementing such a rule would have been left to the discretion of local municipal and county authorities.

Prop 19 supporters included a broad range of politicians, unions and rights groups -- as well as billionaire philanthropist George Soros, who backed the "Yes" campaign with a million dollars of his own money.

Despite the support, a recent opinion poll showed the no vote ahead by 49 percent to 44 percent -- an unexpected blow for the Yes campaign, which has led surveys for months.

Opponents included all the main candidates to succeed Schwarzenegger as California governor -- including the victorious Democrat Jerry Brown -- and for the state's two Senate seat races, as well as US Attorney General Eric Holder.

The former film star Schwarzenegger, a Republican but known as socially liberal, revealed on his Twitter page after voting closed that he was among those who rejected the marijuana proposals.

US federal statistics show nearly seven percent of the state's 37-million strong population smoke cannabis at least once a month.

The proposal has also drawn international criticism.

Last month Latin American leaders meeting in Colombia said the United States could not at the same time "promote penalizing this kind of activity in other countries and authorize the legalization of drug production on their own territory."

US authorities had warned a yes vote could greatly complicate their war on drugs.

But proponents argued that legalizing marijuana could throw a spanner in a very lucrative market for Mexican drug traffickers, who are fighting a brutal drug war for control of trafficking routes into the United States that has claimed over 28,000 lives in nearly four years.