Daily Kos's convention — the in-person gathering of the nation's most-read online political blog — was practically carpeted with presidential candidates. But perhaps the most notable presentation came from Ava Lowery, a 15-year-old from rural Alabama, whose homemade video was shown at the convention on jumbo television screens.

Ms. Lowery's video, set to the Queen song "We Will Rock You," contrasted the "liars" and "leakers" in the Bush administration with "those of us who choose to stand up for truth and justice." Her handiwork, which can be seen at Youtube.com (Ava Lowery's video), is a bit over the top. But it shows that a 15-year-old with video software and Internet access can now create and disseminate a professional-quality political ad.

Last week's gathering was widely described as a bloggers' convention, but it was a lot more. It was the mainstream debut of "Internet-powered politics," and it made a convincing case that the Internet will quickly surpass television as the primary medium for communicating political ideas. This could be good news for progressives, as the Daily Kos community hopes, and for the Democratic Party, which sorely needs some. But like all technological revolutions, Internet-powered politics could have some unintended consequences.

The cutting-edge discussions at YearlyKos were about the intersection of technology and politics. Bloggers sketched out their plans for shaping news in upcoming elections. The liberal political-action group Democracy for America gave a primer on turning online activism into offline activism, by developing networks of supporters and sending out "action alerts" to get them to contribute money and volunteer for campaigns and causes. The Participatory Culture Foundation, a nonprofit group, led a workshop on how ordinary people can make political videos and distribute them over the Internet.

The 2004 presidential election was the first to give an inkling of the Internet's potential, but in 2008 its impact will be much greater. Web sites like Daily Kos will play a growing role in fund-raising, particularly the so-called "money primary," in which candidates prove their worth by raising money early. Bloggers will do more to shape the issues and the debate, and more of their ideas will jump into traditional news outlets. The breakout commercial in the next presidential cycle could be one produced on a teenager's computer and e-mailed from friend to friend.

For the conventioneers, there was no question that Internet-powered politics would do as much — or more — for the left as talk radio did for the right. There are some cultural reasons why Democrats may be more attracted to the Internet. Democrats, as a group, may have warmer feelings about science and technology, or perhaps they are attracted to the decentralized, anti-authoritarian nature of blogs and e-mail (the exact opposite of a show like Rush Limbaugh's, where the host speaks and the "dittoheads" take it all in).

Online fund-raising also makes it easier and cheaper for Democrats to harvest contributions from individuals, a boon for a party that lags in raising money from traditional sources. And with Democrats often significantly outspent on television advertising, low-cost, innovative Internet advertising holds considerable promise. "The best campaigns are going to be the ones that let their supporters do a lot of their advertising for them," predicts Nicholas Reville, co-director of the Participatory Culture Foundation. Video blogs, or vlogs, could help counterbalance talk radio. One day, there could be a Daily Kos television station staffed by volunteer bloggers and sent out over the Internet as streaming video, going up against Fox News.

On Election Day 2008, voters could get video clips on their laptops and cellphones from Beyoncé, Bruce Springsteen or the Dixie Chicks — targeted by geography or demographics — urging them to vote, and telling them where to do it.

It would be a mistake, though, to think that Internet-powered politics will help only one side. The Internet's leveling effect may be a two-edged sword. Bloggers like to fault the decisions made by Democratic Party strategists in Washington, and often they are right. But the Republican Party has succeeded in part because of the tight discipline and well-executed campaign strategies of people like Karl Rove. More input from the "net roots" — the Internet version of grass roots — may help the Democratic leadership avoid some bad decisions. But it may also make Democratic politics even more scattershot compared with the well-oiled Republican machine.

On the whole, the new more participatory politics that the Internet is ushering in is clearly a good thing for democracy. Whether it turns out to be good for the Democratic Party in particular is yet to be seen. But the transformation seems inevitable. As successful as YearlyKos was this year, in 2007 it should be even bigger and more influential. Tom Vilsack, the former governor of Iowa and a likely presidential candidate, is already lobbying for it to be held in Iowa — the site of the first presidential caucuses in 2008.