When David All, a former Republican congressional aide, launched a blog recently that he hopes will spur his fellow Republicans to bridge the digital divide, he did his best to sound upbeat. "Today our Revolution begins," he wrote. "Tomorrow we fight."

But implicit in his cheerleading was the acknowledgment that there is a widening gap between Democrats and Republicans on the Internet, and that his party will have to scramble to catch up. "For the most part Republicans are stuck in Internet circa 2000," he said in an interview.

Another Republican -- Michael Turk, who was in charge of Internet strategy for President Bush's 2004 campaign -- puts the problem his party faces more bluntly: "We're losing the Web right now."

The most recent figures from Nielsen/NetRatings provide one measure of the gap. Looking at the Web sites of presidential candidates from the two parties, it found that former senator John Edwards's site had about 690,000 unique visitors in March, when the Democrat's wife, Elizabeth, announced that she had a recurrence of cancer. That was more than the combined number of visitors to the sites of the three leading GOP contenders, Rudolph W. Giuliani (297,000), Sen. John McCain (258,000) and Mitt Romney (76,000).

There are other measures as well. No Republican comes close to matching the popularity of another Democratic candidate, Sen. Barack Obama of Illinois, on YouTube, MySpace and Facebook, the social-networking triumvirate. The Democrats are ahead in the online money race. The top three Democrats, Sen. Hillary Rodham Clinton, Obama and Edwards, amassed more than $14 million over the Internet in the first three months of 2007; in contrast, the top three Republicans, Giuliani, McCain and Romney, collected less than half of that, $6 million. Furthermore, ABC PAC, the conservative fundraising site, has raised $385 so far for Republican presidential hopefuls; Act Blue, its liberal counterpart, has collected about $3 million for Edwards alone.

One reason for the disparity between the parties, political insiders say, is that the top Republican candidates are not exciting voters the way the Democratic front-runners are. Another is that it takes a certain level of technical skill and understanding to be an online strategist, and Republicans admit that "the pool of talent in the Democrats' side is much bigger than ours."

But an underlying cause may be the nature of the Republican Party and its traditional discipline -- the antithesis of the often chaotic, bottom-up, user-generated atmosphere of the Internet.

"We've always been a party of staying on message," All said. "It's the Rush Limbaugh model. What Tony Snow says in the White House filters down to talk radio, which makes its way to the blogs."

Peter Leyden, director of the New Politics Institute, a San Francisco-based think tank that in recent months has been advising Democratic members of Congress and their staffs on how to take full advantage of the Web, argues that the culture of Democrats is a much better fit in the Internet world.

"What was once seen as a liability for Democrats and progressives in the past -- they couldn't get 20 people to agree to the same thing, they could never finish anything, they couldn't stay on message -- is now an asset," Leyden said. "All this talking and discussing and fighting energizes everyone, involves everyone, and gets people totally into it."

If conservatives have mastered talk radio -- with Limbaugh as the undisputed king of the AM dial -- those on the left hope to achieve the same dominance on the Internet. Daily Kos, a sounding board for opposition to Bush and the Iraq war, among other topics, leads most political blogs in Web traffic and notoriety. Last year, the site spawned Yearly Kos, the first political blogger convention. Its founder, Markos Moulitsas Zúniga, refers to himself as the site's "mayor," with everyone else "doing their own thing, managing their own projects, while I keep the plumbing running."

Moulitsas will concede the influence of conservative blogs and Web sites in the successful attack on Sen. John F. Kerry (D-Mass.) during his 2004 presidential campaign, when he was accused of exaggerating his service record during the Vietnam War, and on CBS News for its reporting on Bush's war record. He also concedes that Republicans have their own popular blogs, such as InstaPundit, RedState and Michelle Malkin's -- sites, he asserts, that are parts "of the Republican noise machine, affiliated to talk radio and Fox News." Malkin, the doyenne of the conservative blogosphere, is a frequent contributor to Fox News.