MADISON, Wis. — To promote his recent campaign for mayor of St. Petersburg, Fla., Scott Wagman bought an ad that popped up online when anyone ran a Google search for his opponents’ names.

He was hardly the first to employ the tactic, which didn’t stop a rival campaign from complaining the ad did not have a “paid for by” disclaimer. The Florida Elections Commission ordered Wagman to remove it and pay a $250 fine, even though the required disclaimer was longer than the 68 characters allowed in the text of the ad, which wasn’t “paid for” until someone clicked on it.

Wagman is fighting the complaint, and his case adds to an ongoing debate about how “old media” rules governing campaign spending should apply to the “new media” of the Internet age. When does a blog connected to a campaign need to disclose its allegiance? Does a candidate’s personal Facebook page need a disclaimer if it is updated by a staffer? Can a campaign-related tweet — a message posted on social media site Twitter — be regulated?

“Policing this is going to be a tremendously difficult thing, let alone writing the rules,” said Edwin Bender, executive director of the National Institute on Money in State Politics, a nonprofit group in Helena, Mont.

Citing the Wagman case, Wisconsin’s Government Accountability Board this month ordered staff to draft guidelines outlining the circumstances under which the public needs to know who is paying for an online ad or Web site. Several political experts said Wisconsin appears to be one of the first states where regulators are drafting such guidelines, and they expect others to follow.

Many states currently require political ads to include disclaimers saying who paid for them, although some exempt items such as bumper stickers, buttons and T-shirts where a disclaimer is impractical.

So far, the Federal Elections Commission has taken a mostly hands-off approach, as campaigns still spend far more money reaching voters through television, radio and direct mail. The commission ruled in 2006 that campaign regulations do not apply to most Internet activity, except for paid political advertising on someone else’s Web site. Bloggers are exempt as long as they write voluntarily and are not paid by a campaign.