The enigmatic Deidara combines fire and earth chakra to set off powerful explosions with his clay animals, and he can even blow himself up like a nuke in emergencies. He was a valuable asset to the Akatsuki, but alas, there are other, even more powerful shinobi who outclass Deidara and his explosive "art."
Tsunade's old squadmate and friend, lord Jiraiya the toad sage, is nearly as powerful as Kisame and Itachi combined. He is certainly stronger than other Akatsuki members like Deidara, Sasori, or Kakuzu. Jiraiya was thrice asked to become Hokage, but he turned down that offer each time despite being 100% qualified for it.
Jiraiya can do nearly anything in battle, from his deadly taijutsu techniques to his boiling-hot oil attacks and his advanced ninjutsu based on his long white hair. Most of all, Jiraiya can summon the mighty Gamabunta, king of toads, and use Sage Mode to triumph over any foe. Deidara wishes he could do any of that.