By Rob Hotakainen

When televangelist Pat Robertson announced his support for legalizing marijuana last year, pot backers wasted no time in putting his picture on an electronic billboard in Colorado.

Marijuana billboards have popped up along busy freeways from Seattle to Florida. In September, one greeted fans going to Sports Authority Field at Mile High in Denver for the first NFL game of the season. In July, pot supporters tried to get a video ad on a jumbo screen outside a NASCAR event in Indianapolis, but objections forced them to pull it at the last minute.

In the latest twist, pro-pot billboards are emblazoned on city buses in Portland, Maine, aimed at winning votes for a Nov. 5 ballot measure that would make the city the first on the East Coast to legalize marijuana for recreational use.

Critics fear that the increased advertising is a sign of things to come as support for legalization continues to grow, reflected by a Gallup poll released last week that found backing from a record high 58 percent of Americans. They see the stepped-up promotion as a dangerous trend that will lead to more drug abuse among children. While the Greater Portland Transit District has banned tobacco ads, it accepted $2,500 to display the marijuana billboards on the exterior of four of its 32 city buses and in two bus shelters. The ads, which debuted early this month, are set to run until Election Day.

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In one ad, a bespectacled woman says: "I prefer marijuana over alcohol because it's less toxic, so there's no hangover." Another features a smiling young man who says he prefers pot over booze "because it doesn't make me rowdy or reckless."

Transit officials say the ads are constitutionally protected political speech since they also encourage a "yes" vote on a city ballot initiative.

"We're allowing this message because it's political speech. It's designed to help change a law," said Gregory Jordan, the general manager of the transit district. "It's not the promotion of a commercial product. ... We don't have a position on the content of the advertising, just that it's a political message and by its very nature it's protected by the First Amendment."

Opponents say the ads go well beyond endorsing a ballot measure, instead promoting an illegal product. They say the ads shouldn't be allowed in places where they're so easily viewed by youths, including high school students who ride city buses to school.

David Boyer, the Maine political director for the Marijuana Policy Project, which bought the ads, said the backlash had surprised him. He defended the ads, saying it's important that everyone, including kids, knows that marijuana is safer than alcohol.

"When you don't talk to kids like they have a brain, then they kind of resent you for it and they end up turning everything else out that you do say," Boyer said. "I think you do the best with them by telling them the truth."

Legalization opponents say marijuana is addictive and should remain classified as a controlled substance.

"We're witnessing the birth of Big Marijuana," said Kevin Sabet, the director of the University of Florida Drug Policy Institute and a former adviser on drug issues to President Barack Obama and Presidents George W. Bush and Bill Clinton. "And I really worry about the messages this advertising is going to be sending to kids, giving them the impression that marijuana is safe."

He said the marijuana industry was relying on similar tactics that had helped advance the tobacco industry: "It's the advertising. It's the billboards. It's the vending machines. It's the lobbying groups, all the things that Big Tobacco has mastered for 80 years."

The Portland vote is the first ballot test for legalization backers since last November, when Washington state and Colorado approved plans to sell and tax the drug for recreational use beginning next year. If the measure passes, residents of Maine's largest city who are 21 and older each will be allowed to possess up to 2.5 ounces of marijuana.

"It would be big for the East Coast, especially New England," Boyer said. "It's just another domino. And this movement has gained tremendous momentum in the last year."

So far, 20 states and Washington, D.C., have approved the use of marijuana for medical purposes. The Marijuana Policy Project has targeted 10 states for full legalization by 2017. If the plans succeed, Alaska will vote next year, followed by Maine, California, Nevada, Hawaii, Maryland, New Hampshire, Rhode Island, Arizona and Vermont.

That means one thing: Expect more ads.

If they get more people talking, the sponsors will be happy.

"People are not used to hearing about marijuana via billboards or bus ads, so they tend to spark quite a bit of public interest and dialogue," said Mason Tvert, the director of communications for the Marijuana Policy Project. "Our goal is to get people thinking and talking to one another about marijuana. We are confident it will lead to greater understanding of the substance and broader support for ending its prohibition."