Comcast is interviewing reporters and editors to staff its online news operations in Chicago, San Francisco and Washington. Its executives are using the same template in these markets that they used in Boston, where Comcast spent millions of dollars earlier this fall to launch a news operation from scratch.

“This is the single largest investment outside of making an acquisition in the business,” said Eric Grilly, executive vice president and chief digital officer for Comcast Sports Group.

The moves clearly are coming in response to ESPN’s launch of locally tailored Web sites. This year, ESPN launched local sites in Chicago, Boston and Dallas, with launches planned in New York and Los Angeles next year.

The implications for Comcast are significant. In markets where it operates regional sports networks, Comcast does not want to cede local sports news to a national entity like ESPN. RSNs believe they have a competitive advantage thanks to the local relationships they have developed with the teams and their fans.

“In the short term, these moves are about protecting existing businesses,” Grilly said. “But without having a strong digital play, our overall business could be siphoned off.”

In the Mid-Atlantic market, for example, Comcast plans to fully staff two Web sites, one for CSNWashington.com and one for CSNBaltimore.com.

“I don’t think anyone outside of the Weather Channel uses the term Mid-Atlantic,” said Rebecca Schulte, senior vice president and general manager of CSN Mid-Atlantic. “It’s too vague to discuss what we’re doing.”

At some point in the first quarter, Comcast will launch a new Web site design for its networks to accommodate more original reporting and video.

In its first year, it expects to have a beat writer hired for every professional team it covers. In ensuing years, it plans to hire reporters to cover local colleges and high schools.

The key for Comcast is to attract big-name writers who could appear on both TV and online.

Comcast dismissed suggestions that its coverage will be compromised by business arrangements the channels have with pro teams in their markets. MLB’s Giants and White Sox hold stakes in Comcast RSNs in the Bay Area and Chicago, respectively. And Comcast SportsNet Mid-Atlantic is the official cable network of the Washington Redskins.

“We do it every day in our news right now,” Schulte said. “We take the good with the bad. Our business relationships don’t taint what we do in our news bureaus.”

Comcast plans to launch a blog area called Truth and Rumors, where it expects many of its columnists to write online. It also will launch lifestyle and entertainment aspects to the Web sites.

Grilly expects many of the Web-based shows eventually to migrate from the Web to television. For example, the company plans to launch pre- and postgame shows online, which then could cross over to television.

The moves already have showed significant progress in Philadelphia, where unique visitors and time spent on the Web site both doubled since the market’s RSN started hiring new reporters about eight months ago.