The failure of Prop. 19 – a California legalization measure – two years ago was widely seen as a stunning defeat for high-flying pro-marijuana forces.

Yet judging by three new pot legalization proposals now on ballots in Washington, Oregon, and Colorado, the lessons of Prop. 19 were hardly lost.

Instead, pro-legalization groups including the ACLU studied exit polling, conducted their own focus group research, found moderate spokesmen, and tweaked proposals to try to build “trust” with a middle America that has grown steadily more accepting of pot use, yet, as Prop. 19 showed, remains wary of the impact of making the drug legal.

Three weeks ahead of Election Day, it now appears that at least one of those initiatives – Initiative 105 in Washington State – is heading toward passage, with some 57 percent of likely voters now backing the measure, according to a Survey USA poll taken in September. If that happens, it would be the first time a government has lifted pot prohibition, setting up a potential Constitutional showdown with a federal government that still prohibits growing, selling, and using marijuana.

But more critically, a successful legalization campaign in Washington would give the strongest evidence yet of how pro-marijuana groups can spin a winning message to the American center, even against entrenched and deputized opposition. How closely the promise of that message dovetails with the reality of legalization, however, will be the real test for broader adoption.

“I think these campaigns did learn a lot from the Prop. 19 experience,” says Beau Kilmer, co-director of the RAND Corporation’s Drug Policy Research Center.

“There were a lot of meetings after the fact and there’s some serious money [involved], all of which makes it easier to tease out potential liabilities and run a campaign where you’re doing focus groups and you have lots of televised advertisements.”

The initiatives in the three states differ slightly, but all have managed to cobble together ideologically diverse coalitions. They’ve also managed to balance societal safeguards with the promise of sizable tax revenues. Where Prop. 19 left it to municipalities to license growers and retailers, the new measures impose state regulation on the pot trade. And proponents have also picked a presidential election that’s likely to draw lots of younger voters and stuck to libertarian-leaning Western states to make their case.

In Washington State, Initiative 105 combines a 25 percent excise tax that could raise nearly $2 billion over the next five years with a ban on pot smoking in public, an intoxication limit of 5 nanograms of THC per milliliter of blood, and an exception that would allow employers to fire workers for smoking on the job.

That “not-in-your-face” tack is proving powerful enough that some of America’s biggest drug warriors are challenging US Attorney General Eric Holder to do something to help sway attitudes away from Initiative 105.

On a conference call Monday, several former senior DEA officials and directors of the Office of National Drug Control Policy said Washington should make it clear to voters that even if states pass the initiatives, pot smokers in those states would still be violating federal law.