Sources claim the pop hunk is clashing with other group members because he wants to transform their sound after the summer sell-out tour to make them "cooler".
The swordsman wants the group to write more of their own songs and ditch their high profile songwriting team.
But his bandmates, especially Niall Horan and Louis Tomlinson, are less than impressed with his ideas.
Harry's dramatic plans are believed to have been hatched after hanging out with stars including The Rolling Stones, Elton John and Rod Stewart, who have urged him to take the next big step.
A source close to the band revealed: "Harry loves being in the band and respects and loves his bandmates. But he's very ambitious and thinks they should be growing up more and becoming more credible.
"Their third album Midnight Memories was already a lot less pop but Harry wants to push it further.
"He thinks their next album is the perfect time to create a much edgier and more rock 'n' roll image and he's already writing songs that he wants them to include on the record.
"The problem is the rest of the band fear if Harry starts changing their style he's going to take over the whole thing.
"They all have different ideas on what direction they want to take musically and they are becoming more and more vocal about it.
"Niall and Louis especially are worried about turning their backs on a pop sound and changing a winning formula.
"The fear is that if Harry doesn't get his way he could end up walking out and going solo.
"He doesn't want to be five years down the line and still doing boyish pop tunes."
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