But wouldn't you say that Naruto was only so persistent because he had the power to back it up?
No. Power had only a slight thing to do with it, but this is due to the back and forth power growth they shared due to the Indra/Ashura factor Kishi wrote in.
If we disregard the power gap between Naruto and Sakura. Naruto still had far greater determination to accomplish his goals and a much greater bond/relationship with Sasuke vewing him as a brother, compared to Sakura's superficial Crush of Sasuke.
This primarily goes back to Naruto's character motivations of being sort of thick headed and wanting to prove people wrong. "Becoming the Hokage", his ninja way blah blah blah. He always wanted to do things his "ninja way", and shape his life through action.
After the many back and forth bonding and rivalry moments in part 1 and VOTE fight. Naruto made a promise to Sakura and became obligated by virtue of his nindo. Being taught by Kakashi that your comrades are more important than finishing missions, and after from Jiraiya how he gave up on saving his best friend Orichimaru. Naruto's goal was to prove himself he could do it. It's just a part of his character as the brash
knuckled headed won't take no for an answer Ninja.
Do I need to mention all the times Naruto and Sasuke risked their lives for each other in part 1?
That's rich