SALEM, N.H. — Obama Girl has upset Obama’s girls. The Web video of a scantily clad actress pledging her affection for Senator Obama, a Democratic presidential candidate, has been a hit online, but not in his own home. Mr. Obama says his 6-year-old daughter Sasha has noticed news coverage of the video.

“Sasha asked Mommy about it,” Mr. Obama said yesterday in an interview with the Associated Press. “She said, ‘Daddy already has a wife’ or something like that.”

“I Got a Crush on Obama” stars an aspiring model and actress named Amber Lee Ettinger, aka Obama Girl. Her song, which has lines like “Universal health care reform, it makes me warm,” has gotten more than 3 million hits and nearly 10,000 comments since being posted two months ago on YouTube, the online video-sharing site. Mr. Obama, a Democrat of Illinois, said he knows the video was meant to be lighthearted, but he wasn’t smiling when asked about it in the interview.

“I guess it’s too much to ask, but you do wish people would think about what impact their actions have on kids and families,” Mr. Obama said during the interview, held in the den of a supporter who just had hosted a campaign stop on her front lawn attended by about 120 people.

“This is part of the process of politics that can be difficult, [that] is making sure that your kids and your wife and your family are insulated from both things like this and what I suspect will be at some point some negative campaigning,” Mr. Obama said.

When the campaign gets negative, Mr. Obama said, he’ll be able to be tough without being inconsistent with his call for a new politics of hope.

“I feel pretty comfortable about the tone that we’ve taken during the course of this campaign,” Mr. Obama said. “I think I’ve been respectful of all the candidates. I would challenge anyone to find a statement that I’ve made that has been personal as opposed to a substantive difference with a candidate.”

He said calling Senator Clinton’s refusal to negotiate with rogue foreign leaders “Bush-Cheney lite” didn’t cross the line. Mrs. Clinton responded to that earlier comment by asking, “What’s ever happened to the politics of hope?”

“The Clinton campaign reacted as, ‘Oh, whatever happened to the politics of hope. That’s negative campaigning,'” Mr. Obama said. “If you actually look at the quote, I wasn’t accusing her of being Bush.”

“If Senator Clinton thinks that we should to continue with that type of approach of setting preconditions before we meet as opposed to preparation, then that is a light version of that policy,” he said. “So that wasn’t a sort of personal attack or an ad hominem attack. That was a very specific argument about the need to break away from some of this administration’s policies. That is inevitable. Otherwise we’re not going to be having any conversations during the course of this debate, other than a bunch of platitudes.”

Mr. Obama said he understood the view of a New Hampshire voter who warned him last week to avoid public spats with his Democratic rivals or risk becoming part of politics as usual.