CBS News Correspodent Howard Arenstein reports those are the findings of the new study by the Committee of Concerned Journalists. Tom Rosenstiel, the Committee's vice chairman, said some Web sites offer all the content of a good newspaper plus other political information, such as biographies of candidates and video of debates.
But Rosenstiel added other sites are managed by people with little news judgment and are updated frequently but for no particular reason.
Some political Web sites do not offer links to related Internet sites featuring unfiltered information - such as transcripts of politicians' speeches, for instance, as opposed to reporters' stories about them.
And some are just hard to find.
"Scroll, click, scroll, click, scroll, click. Whew," the study said, detailing the steps needed to reach them.
Once accessed, political news was plentiful. Two-thirds of all the "front pages" of the Web sites examined had at least 16 stories related to the campaign, the study said.
Yet substance was sparse. Only 2 percent of the lead stories dealt with the candidates' policy positions, their records or core beliefs.
Still, the top political stories found on the Internet were well-sourced, according to the study, which monitored two national newspapers and 12 Internet sites on six days of the primary season between late February and Super Tuesday, March 7.
"Contrary to the idea that the net is full of opinionated argument or unsubstantiated innuendo, campaign sourcing on the Internet was strong," the study said. "More than one in five of all lead stories had more than seven sources. And overall, more than half had at least five sources."
Almost one-quarter of Americans say they now get some election information from the Internet, the Pew Research Center for the People and the Press reported in a survey released in February.
And in a study last month, the Annenberg Public Policy Center reported more Americans were surfing the Internet for political news at a time when the three major television network newscasts averaged just 36 seconds a night about presidential candidates.
"I think that it's pretty clear that the potential of the Internet has not been fully tapped," said Rosenstiel, director of the committee's Project for Excellence in Journalism.
"The sites that are mixing video, audio, newspaper and wire service stories and making it easy to find, they're the ones that are tapping the potential of the Web."