More than 15,000 people will converge on Boston later this month to cover the Democratic National Convention -- including, for the first time, bloggers.

The Democratic Party plans to give media credentials to a select group of bloggers who want to cover the event, where Sen. John F. Kerry (Mass.) is expected to accept his party's presidential nomination. The group has not announced which bloggers might get the passes, but that information will come in the "next few weeks," an event spokeswoman said. The convention begins July 26.

But officials said whoever gets credentials will have the same opportunities to cover the four-day event that journalists enjoy. "We want to treat them just the same as other reporters," said Mike Liddell, the convention's director of online communications. "We're even planning to do a breakfast for them the first day of the convention."

The Republican Party recently decided that it will also give bloggers credentials for its convention later this summer. A spokesman for the event said it is still working out details.

The Web sites, which are essentially online journals, have become a prominent campaign tool this election season -- ever since former Democratic presidential candidate Howard Dean's official blog caught on. Since then, scores of other candidates have developed similar sites. Some candidates have begun advertising on other independent blogs -- especially sites that feature commentaries, usually partisan, on the political news of the day.

But neither party has ever allowed bloggers to cover one of its presidential conventions firsthand -- and the decision seems to promise a clash of two very different cultures. The conventions have become carefully staged productions intended, primarily, to reintroduce the parties' nominees to the general public. Independent blogs -- especially those focusing on politics -- are far more freewheeling, their authors mixing fact with opinion and under no obligation to be either fair or accurate.

Joe Trippi, former campaign manager for Dean's campaign, said he supports the decision but that it presents some risk to the Democrats. He said many bloggers are more liberal than Kerry -- and may feel free to vent their frustration with the candidate if, for example, he presents himself at the convention as a centrist.

"They're much tougher, I think, from an ideological bent than mainstream press," Trippi said. "You're not going to take any flak from the mainstream press for tacking to the center on a given issue."

But he and other Democrats said the plan also gives the party a chance to reach a larger audience. Although television networks have cut back on their coverage of the conventions -- saying they yield little news -- some bloggers have attracted sizable audiences. Lina Garcia, a spokeswoman for the convention, said she hopes the bloggers will help the party reach young people. "A lot of young people blog now, and they're important to us," she said.

Markos Moulitsas Zuniga, a Berkeley, Calif.-based lawyer who runs one of the most popular liberal blogs -- Dailykos.com -- predicted that many bloggers will beam a reliably pro-Democratic message back to their readers. "We're all partisan. We don't pretend to be otherwise and would not be constrained by bounds of having to balance out what we write with the other side," he said. "So it's a much more direct way to get out the party's message to its constituents and potential constituents."

It is not clear how the Democratic Party will decide among the more than 60 bloggers who have applied for credentials. Convention officials said they are considering three criteria: the size of the blogger's audience, the "professionalism" of the site and the amount of original material it includes. It is subjective and a little vague. But then again, Liddell said, no one has tried this before. "We don't have a guide to go by," he said.