By Sima Kotecha
Newsbeat US reporter
Presidential candidate Barack Obama has been accused of becoming a global celebrity
What do socialite Paris Hilton, pop star Britney Spears and presidential candidate Barack Obama have in common?
According to Republican presidential hopeful John McCain, Obama is nothing more than a lightweight celebrity just like the two US starlets.
McCain's new ad shows Obama addressing a huge crowd with images of Spears and Hilton flashing up.
A voiceover said: "He's the biggest celebrity in the world. But, is he ready to lead?"
A spokesman for TV reality star Hilton, said she was "neither asked, nor did she give permission, for the use of her likeness in the ad, and has no further comment".
Team Obama has dismissed the commercial calling it "baloney" and "baseless".
McCain's manager Rick Davis compared Obama to Hilton on a US news programme.
"Barack Obama has become a global celebrity. Barack Obama has more fans across the world than Paris Hilton does. It's just an extraordinary thing and I don't think anybody would under estimate that," he said.
Obama said he has "never even met the woman" and dismissed all the comments saying McCain "doesn't seem to have anything positive to say about me".
The competition between McCain and Obama is hotting up
But McCain's attacks don't stop there.
He has also suggested the democrat is high maintenance, just like a celebrity.
"Obama likes chocolate protein bars, black forest berry honest tea, and arugula."
Obama has counter-punched his 71-year-old rival with his own ad showing images of the Republican contender with President George Bush and accusing him of practicing "the politics of the past".
Obama also chose to have a pop at McCain's $520 Italian calfskin shoes.
It wasn't clear what they were saying about them apart from he wears them a lot and they are expensive.
Consistent and aggressive
Political experts say the bantering between the two has got ugly, very early.
Usually in presidential campaigns the nasty stuff comes out closer to the election.
But the timing makes perfect sense.
With Obama hogging the media limelight, McCain's team realise they've got to define their rival before he defines himself through his own publicity.
Therefore, their attacks are deliberately consistent and aggressive.
Obama on the other hand, needs to keep up and show Americans he's capable of holding his own.
He's still struggling to convince voters he can be a good commander in chief and that's something he's got to overcome if he wants to make history by becoming the first US black president.