SACRAMENTO — Under new rules approved Thursday, the state hopes to help Californians determine whether political material they read online is a writer's own opinion or propaganda paid for by a campaign.

Campaigns will now have to report when they pay people to post praise or criticism of candidates and ballot measures on blogs, Twitter, Facebook, YouTube and other websites.

"The public is entitled to know who is paying for campaigns and campaign opinions," so voters can better evaluate what they see on blogs and elsewhere online, said Ann Ravel, who chairs the California Fair Political Practices Commission.

Open-government groups endorsed the new rules, which govern "favorable or unfavorable" content — although much of the time that information may come weeks or even months after publication. Bloggers and some others say the rules infringe on free speech.

The regulations require disclosure by campaigns that pay someone $500 or more to post positive or negative content on Internet sites not run by the campaigns. In periodic spending reports required by the state, the campaigns would have to identify who was paid, how much and to which website or URL the posting was made.

Campaigns may skip such reports for posts identified on the website as paid for by a campaign. An example given by the commission was: "The author was paid by the Committee to Re-Elect Mayor Jane Doe in connection with this posting."

Because campaign spending reports are filed months apart, readers may not know while they are reading something that the information was paid for.

That could be addressed with additional rule changes, to require more immediate disclosure of campaign spending, said Kathay Feng, executive director of California Common Cause.

The new rules are "a step in the right direction and … a very important step," Feng said. But "there shouldn't be a time lag as a way of hiding the ball from voters."

Rival campaigns and the media will make the public aware of which sites are using paid campaign content, said some of the measure's supporters.

The open-government group Consumer Watchdog praised the new regulations for aiming "sunshine" at a new and growing field of political communication.

"It's about ensuring that the voting public knows that paid bloggers … should be viewed through the same prism as political advertisement and direct-mail pieces," Daniel Palay, a Consumer Watchdog spokesman, told the commission Thursday.

Ravel had proposed last year that bloggers and others be required to disclose when political interests are paying for their content, but that raised the ire of Internet activists and she scaled the measure back.

"Any type of compulsory disclosure by a publisher is going to raise 1st Amendment issues," said David Greene, a senior staff attorney at Electronic Frontier Foundation, a San Francisco-based group that advocates for Web users, including bloggers.

"You are always concerned about anything that is going to chill someone's participation in the public debate," he said.

Steve Maviglio, a frequent political operative who regularly blogs on the website California Majority Report, said the rules, which take effect in about a month, will be onerous and ineffective.

"Although well-intentioned, it will prove to be unworkable and unenforceable, creating mountains of paperwork that will ultimately lead to chilling the rapid growth of social media in campaigns," Maviglio said.

The maximum fine for a violation is $5,000.

Officials said decisions on whether violations occur will be made case by case.

patrick.mcgreevy@latimes.com