Haku and Kimmimaro were to stay behind to guard Konohagakure. This mission team would primarily consist of Uzumaki Naruto's squad, with Uchiha Yuka temporarily assigned to join them, forming a three-person unit alongside Naruto and Sakura. Since both Naruto and Yuka were still Genin, Kakashi would also be needed to lead the team.
Nara Shikamaru was only responsible for assigning missions. Hyuga Neji's task was not to go to Sunagakure to rescue Gaara; they had to finish their current assignment before they could provide support.
Konohagakure was short on manpower, but dispatching a Jinchuriki to rescue another Jinchuriki would, to a certain extent, demonstrate Konohagakure's sincerity to Sunagakure.
Chapter 257