They were put together as equals on the 2010 series of X Factor.
But One Direction’s U.S. management are trying to make Harry Styles into the lead singer, with sources saying boybands in America that have a recognised frontman tend to make it bigger than those that don’t.
The teenager, who turns 18 today, has been given leading roles during their current tour stateside.
The ex-boyfriend of The Xtra Factor host Caroline Flack was yesterday continuing the publicity round with his band mates- Louis Tomlinson, 20, Zayn Malik, 19, Niall Horan, 18, and Liam Payne, 18.
Harry led the band when they filmed a guest spot on Nickelodeon show iCarly, with Carly, played by Miranda Cosgrove, 18, developing a crush on him.
A source told The Daily Star: ‘Columbia music execs are rubbing their hands with glee. It looks like One Direction are going to be absolutely massive in America.
‘They decided long ago that Harry is a natural frontman. He’s funny, confident and has a great voice.’
But the group are keen to stick together.
A friend told the newspaper: ‘They are determined to carry on the way they have been – without a lead singer. Harry certainly hasn’t asked for all this attention.’
Harry has already caught the eye of the offspring of Hollywood royalty, Katherine Schwarzenegger, daughter of action man Arnold.
After tweeting last week that she thought he was cute after watching one of the band’s videos, she managed to blag her way onto the iCarly set.
But Harry is wary of her tough-taking, former governor father.
According to the Sun, he said: ‘Katherine’s been in the studio watching us. Imagine having Arnie as your dad-in-law.’
Then, doing his best Arnie impression, Harry added: ‘Leave my house if you want to live.’
The previous day, Katherine tweeted: ‘Just watched my first One Direction video with my cousin and @Harry_Styles is a cutie indeed!’
It was revealed last week that harry had broken up with his cougar lover Caroline, 32, after three months together.
He wrote on twitter: ”Please know I didn’t “dump” Caroline. This was a mutual decision. She is one of the kindest, sweetest people I know.’
Miranda clearly had a good time on set, tweeting afterwards: ‘Had a lotta fun yesterday w/ @NiallOfficial @Harry_Styles @zaynmalik Louis_Tomlinson and Real_Liam_Payne! It’s gonna be a funny episode!’
And hundreds of U.S. fans were waiting for the band at LAX airport and hundreds more have been camped at their hotel.
Harry said: ‘We have had to use the hotel service lift. There are girls in the main lift the whole day, just going up and down hoping to bump into us.’
The group have not yet released any music yet but pre-orders for their debut album are massive.
They will this month soon go on a U.S. tour with boyband Big Time Rush.