It depends how cocky Deidara gets as the fight goes on (he doesn't like using his good moves, as they supposedly "cheapen" his art). Yet I have a feeling that he may feel more inclined to do so if it's the only way he's going to win. I doubt that C1 is getting through Iron Skin and C2 is debatable. His defense combined with flying hearts that spam giant elemental jutsu might just make him reconsider...
I have some faith in Deidara though. I truthfully never thought he wasn't going to beat Gaara when reading the chapter, who had huge offense and an almost impeccable defense on his side. Deidara has: gotten away from Gaara's rather fast sand more then once; dodge several attempts at Naruto and the company to capture him; including the first KN0 charge in mid-air; Naruto's second attempt to Rasengan his face off, Team gai's ambush with no arms; getting his hands pinned down while falling towards his own mines; escaping Sasuke despite his fast speed, and forming a clay clone as a feint for Sasuke to get closer. This is all pretty fantastic on his part considering most people don't consider him as a speedster (probably the whole long-range stereotype)