CONCORD, N.H. — A top aide to Rep. Charles Bass resigned yesterday after disclosures that he posed as a supporter of the Republican’s opponent in Web log messages intended to convince people that the race was not competitive.

Mr. Bass’s policy director, Tad Furtado, posted messages to two liberal blogs whose operators traced the postings to the House of Representatives’ computer server. Mr. Bass’s office traced the messages to him, the Capitol Hill newspaper Roll Call reported Monday.

Mr. Bass issued a statement announcing Mr. Furtado’s resignation.

“Tad Furtado posted to political Web sites from my office without my knowledge or authorization and in violation of my office policy,” Mr. Bass said. “I have referred this matter to the House Committee on Standards of Official Conduct for their review.”

Posting as IndyNH and IndieNH, Furtado professed support for Democrat Paul Hodes but scoffed at a poll showing him tied with Mr. Bass and suggested Democrats should invest their time and money elsewhere.

“I am going to look at the competitive race list to figure out where to send another mydd.com/netroots donation and maybe help out in other ways,” IndieNH wrote. “Maybe CT or NY for me — they are at least close by. Anyone interested in pooling NH efforts for some of those races?”

Laura Clawson, who runs “Blue Granite,” and Michael Caulfield, who runs “NH-02 Progressive,” said they were suspicious of IndieNH’s postings from the beginning.

“You see this all the time on political blogs, some elaborate act where someone says, ‘Now, I hate to say something against a Democrat, but,”‘ Ms. Clawson told the Concord Monitor. “So you develop an eye for it. And this poster definitely tripped all the wires.”

After tracing the poster’s IP address, Ms. Clawson posted an article last week on the results, and the postings stopped.

Mr. Bass said that, although he had not known about the postings, he took responsibility for his staff’s actions. “I sincerely apologize to anyone whose Web sites may have been disrupted by these posts,” he said.

A spokesman for Mr. Hodes, Reid Cherlin, called the postings “at best a dirty trick and at worst a serious offense.”

“If Charlie Bass can’t beat us on the issues, maybe he feels like he’s got to turn to impersonating people on the Web,” he said.

A similar hullabaloo occurred in New Jersey earlier this month, when a liberal blogger accused a campaign staffer for Republican Senate candidate Tom Kean Jr. of using aliases to pose online as an “ardent Democrat.” Mr. Kean denied the accusation.