Democratic candidate Tim Kaine speaks during a Senatorial debate for the Virginia U.S. Senate seat with Republican candidate George Allen on Thursday, Sept. 20, 2012 in McLean, Va. (Evan Vucci/AP)

With tweets, texts and the rise of social media, the political campaign industry is racing to adapt to new technologies. And the dirty tricks industry is adapting right along with it.

On Monday, the U.S. Senate campaign of Timothy M. Kaine began getting reports from concerned supporters in the Hampton Roads region: Someone was sending them anonymous text messages accusing Kaine of calling for a “radical new tax on all Americans.” The text included Kaine’s campaign phone number, and urged people to call him and tell him not to raise their taxes.

The Kaine campaign quickly called on Virginia Attorney General Ken Cuccinelli II to investigate; his office said Tuesday that it could not confirm or deny the existence of any probe. The campaign of Kaine’s opponent, fellow former Virginia governor George Allen (R), said it had nothing to do with the calls. The state Republican Party said the same.

Kaine’s camp also dubbed the calls “misleading.” Although Kaine said in a debate last week that he would be “open” to the idea of a minimum federal tax level for everyone, he did not actually endorse the concept.

So who sent the texts, and how many Virginians actually received them? It’s not clear, and may never be, even though they appear to violate federal law — it’s illegal to send unsolicited text messages to a person’s mobile phone.

Anonymous, automated phone calls are a staple of election season, and with a few rare exceptions, the sources of the calls are almost never found. Now the same is true with texts, which have popped up in the presidential race — Mitt Romney was a victim during the Republican primaries — and scores of other campaigns.

“It’s the digital equivalent of robocalls,” Brett G. Kappel, a Democratic campaign lawyer with Arent Fox, said of the text messages. And with robocallers, or even senders of anonymous “snail” mail, Kappel noted that “they don’t get caught.”

Kappel and a partner at his firm helped persuade the Federal Election Commission to allow campaigns to use text messages for a legitimate purpose — receiving donations. The FEC approved the idea in August, and the campaigns of President Obama and Romney are already accepting such contributions.

Campaigns large and small use text messages for a host of other purposes, including rallying supporters to events and reminding them to vote. The Obama campaign has collected millions of mobile phone numbers, in part by promising some exclusive information — in 2008 the campaign officially revealed Obama’s vice presidential pick via text.

Kaine himself does not use texts. “Our campaign doesn’t even have a text message program!” his team boasted in a Monday fundraising e-mail that cited the anonymous texts. Allen’s campaign would not say whether it has such a program.

But people have to opt in to receive such messages. Otherwise, the senders run afoul of the Telephone Consumer Protection Act of 1991, which established guidelines for the use of automated calls. The rules are especially strict for mobile phones: Neither recorded voice calls nor automated texts can be sent to cellphones without the consent of the recipient.

Earlier this month, the Federal Communications Commission sent out an “enforcement advisory” specifically reminding political campaigns about the rules of the electronic road. The FCC action came after CTIA, the wireless industry trade group, reported an increase in customer complaints about unwanted text messages from campaigns.

“We have seen an uptick, both with text messaging and calling” mobile phones, said Jot Carpenter, CTIA’s vice president for government relations.

Kappel and Carpenter both said it was unlikely that authorized campaign committees or major parties would violate the texting rules. But third-party vendors are harder to track and punish.

“We’d very much like to see the bad actors driven out of this space,” Carpenter said.