Mark 15:12

‘And Pilate again answered and said to them, “What then shall I do to him whom you call the king of the Jews?” '

Note the continual repetition of the title, ‘the king of the Jews' by Pilate. In his experience people who had borne that title had been popular with the people. So Pilate possibly hoped by this question to obtain the request for a further release which would have nicely solved his problem. At a cry of ‘release Him' he could be magnanimous and achieve his object at the same time. And in normal circumstance that might well have been what he would have got. The crowd, if they knew of Him, probably had nothing against Jesus, except that they might see Him as being too soft on the Romans (unless they had learned that he was a rumoured Temple destroyer). But the Chief Priests and their bullies would have nothing of it, and Barabbas' supporters were only really interested in obtaining Barabbas' release. From their point of view this man could easily be sacrificed if it meant getting their own way. He certainly must not be allowed to get in the way of Barabbas' release. So let Him take Barabbas' place. Let Him be crucified instead.