Continued from page 1

The White House said that the blog post by Mr. Phillips, who has a background in politics, was vetted by the communications office. But an administration spokesman did not answer questions about whether the vetting process for the White House blog, which has become a central part of, is the same as the one used for other public communications.

Mr. Issa, in his letter, requested information about why and how e-mails were apparently sent by the White House last week to everyday Americans who had never asked to be contacted by the administration.

Fox News, in particular, has collected hundreds of e-mails received by people who said they never signed up for communication by e-mail or otherwise from the White House. The e-mail sent last week, and received by people who say they did not ask for White House communication, was written by David Axelrod, a top adviser to the president, on the topic of health care reform.

Mr. Issa, in his letter, asked the White House whether “political or commercial e-mail address lists were used” to add people to the administration’s recipient list.

Mr. Phillips noted in his blog posting that “it has come to our attention that some people may have been subscribed to our e-mail lists without their knowledge - likely as a result of efforts by outside groups of all political stripes - and we regret any inconvenience caused by receiving an unexpected message.”

He said that the White House Web site had increased the security of its mailing list and blamed “bloggers and others in the media that have invoked a variety of sinister conspiracy theories.”

“It’s clear that a lot of Americans appreciate getting updates from the White House,” he said.