Text messaging is posing both new opportunities and dangers for America's political campaigns.
The most widely used form of mobile communication, it has become one of the most effective ways for campaigns to reach supporters, using 160-character messages to encourage last-minute donations or provide information such as where to vote. And strict federal rules prohibit such texts from going to anyone who does not "opt in" to receive them.
But some groups have found their way around that requirement, using email _ rather than the SMS "short code" that telemarketers normally use _ to send unsolicited, anonymous and often negative messages to cellphone lists they purchase through brokers.
That texting practice has angered voters, who are forced to pay if they don't have flat-rate messaging plans. And it's alarmed campaign strategists, who fear political texting will be weakened by the introduction of what amounts to spam texting.
"They've taken a tool and technology we used to help people get voter information and turned it into a very sophisticated way to do voter suppression tactics and annoy people with false and misleading information," said Scott Goodstein of Revolution Messaging, a Democratic-leaning mobile communications firm. "Worse yet, people are being charged to receive these messages."
Goodstein has filed a complaint about the practice with the Federal Communications Commission, whose Telephone Consumer Protection Act prohibits telemarketers from texting "to any telephone number ... or any service for which the called party is charged."
Unsolicited messages hit the presidential campaign this year, when texts targeting Republican Mitt Romney surfaced in Colorado, South Carolina and Michigan. Voters received texts urging them to call a number where they heard a recorded message criticizing the former Massachusetts governor.
Spam texts have popped up in congressional campaigns in states including Michigan, North Carolina, Pennsylvania and Missouri and Minnesota. They've also appeared in several state legislative races.
Some of the texts have been followed back to Americans in Contact PAC, a Republican-leaning group whose mission is "to identify social and fiscal conservatives throughout America and engage them at the grassroots level in the political process." Several voters in Wisconsin received messages from txt(at)aicpac.org during Gov. Scott Walker's clash with public employee unions last year, asking, "Do you agree government unions are being too greedy?"
A spokesman for the group did not respond to emails and phone calls seeking comment.
The emergence of such unsolicited texting comes as campaigns have redoubled their efforts to incorporate text messaging into their broader communication strategy.
President Barack Obama's 2008 campaign largely pioneered the use of political text messaging. That's the way supporters were alerted that Obama had selected then-Delaware Sen. Joe Biden to be his running mate, for example.
This year, with social media outlets like Twitter and Facebook a much greater political communications tool than they were in 2008, the Obama re-election campaign is using texts more selectively.
"Texts should be action oriented," campaign spokeswoman Katie Hogan said, suggesting that supporters would receive a text letting them know the location of a volunteer phone bank or a local campaign appearance by the president.
"It has to be relevant to the user of that platform. And you can't abuse the platform,' Hogan said.
Strategists for Romney, the favorite to be the Republican presidential nominee, have been building up the campaign's texting program in hopes of competing with Obama for the number of supporters it reaches.
"Texting is the cleanest channel available to engage with supporters," Romney digital director Zac Moffatt said, adding that the proliferation of third-party groups spam-texting voters was "a real problem for us. People blame the campaign."
Political text spamming has also created challenges for the mobile telephone industry, which reaps significant profits through text messaging and so is eager to halt any mischief that undermines consumers' use and confidence in texting.
Greg Stuart, the CEO the Mobile Marketing Association, the industry group representing mobile carriers, said the group may file its own FCC complaint against unsolicited political texts.
"Any mistrust created in a communications channel is absolutely unacceptable. It destroys consumer's trust in other valid legitimate communication," Stuart said.
Associated Press researcher Julie Reed in New York contributed to this story.
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