CONCORD, N.H. - Barack Obama accused Republicans on Friday of trying to shift the focus of the presidential debate away from serious issues such as the economy and toward frivolous subjects like lipstick, Britney Spears and Paris Hilton.

Taking on a feistier tone, the Democratic presidential hopeful sought to show his supporters he wants to fight back aggressively against escalating attacks by his rival John McCain.

Democrats have become concerned about the momentum gained by McCain and his new running mate as polls have shown McCain has pulled even or slightly ahead of Obama, erasing the lead the Democratic presidential nominee held throughout the summer.

“You’ve seen the other side not want to spend any time talking about the issues,” Obama said. “I mean, what have they been talking about? They’ve been talking about lipstick. They’ve been talking about pigs. They’ve been talking about Britney. They’ve been talking about Paris.”

“These are serious times and it requires a serious debate,” he said. Obama was referring to a blitz of ads McCain has run, including one that likened him to celebrities such as Britney Spears and Paris Hilton.

In another ad, McCain accused Obama of trying to smear Palin, an Alaska governor and self-described “hockey mom,”  when he likened the Republican’s plans for government reform to putting “lipstick on a pig.”

The McCain campaign has suggested that Obama was making reference to Palin’s joke that the only difference between a hockey mom and a pit bull was lipstick but Obama’s campaign denies his comment had anything to do with Palin.

Some of Obama’s backers worry that Obama won’t push back hard enough against the kind of “Swift Boat” attacks used against Democrat John Kerry in his failed 2004 White House bid.

But Obama has been emphasizing he is not going to shrink from the fight against tactics he compares to those of President George W. Bush’s strategist, Karl Rove.

“Here’s what I can guarantee you: We are going to be hitting back hard. We have been hitting back hard. We have been hitting back hard but we’re hitting back on the issues that matter to families,” Obama said earlier in the day at an event in Dover, N.H.

Obama was responding to a question at a town-hall style event from 39-year-old Glenn Grasso, who pressed the Democratic candidate on how he would respond to Republican “attack ads and the smear campaigns.” 

Click here for more Reuters 2008 campaign coverage. 

- Photo credit: Reuters/Mike Segar (Obama at forum on national service in New York on Sept. 11). ABC handout (McCain appearance on The View).