Of course Pilate is not portrayed as a Christian, or even a good man, let alone a saint. However, nearly all bible commentators agree that Pilate was trying to avoid crucifying Christ. Undoubtedly it was political pressure from the Jewish leaders that forced his hand against his own will.
First Pilate really did not care about the silly religious infighting of a strange people. He just wanted to govern and avoid major conflicts like any governor does. He first tried to avoid crucifixion by the penalty of scourging:
Then Pilate took Jesus and flogged him. (John 19:1, ESV)
Then Pilate went out again and said to them, “See, I am bringing him out to you that you may know that I find no guilt in him.” Which shows his intention, that they would recognize this is silly to kill an innocent man over what he saw as just dumb religion. For Pilate, if anything, seemed more like an atheist in his words, ‘What is truth?’
He could not avoid the blood-thirst of the crowd, so in exasperation said:
“Take him yourselves and crucify him, for I find no guilt in him.” (John 19:6, ESV)
Then The Jews threatened him with political pressure:
The Jews answered him, “We have a law, and according to that law he ought to die because he has made himself the Son of God.” 8 When Pilate heard this statement, he was even more afraid. (John 19:7-8, ESV)
Pilate's main ambition was to release Jesus but the fear of seeming disloyal to Caesar made him go against his own conscience:
From then on Pilate sought to release him, but the Jews cried out, “If you release this man, you are not Caesar’s friend. Everyone who makes himself a king opposes Caesar.” (John 19:12, ESV)
To counter his fear of Caesar, he had an opposing fear and reluctance to kill an innocent man, for we find in Luke his wife had a dream (omen) and warned Pilate not to do it:
Besides, while he was sitting on the judgment seat, his wife sent word to him, “Have nothing to do with that righteous man, for I have suffered much because of him today in a dream.” (Mathew 27:19, ESV)
Under all these pressures from his own conscience and his wife, although not a believer in Christ, but simply from the human aspect of not wanting to kill and innocent man and fearing what bad luck might follow the 'omen', Pilate feared Caesar more. While making a last ditch effort to free Jesus by offering him up as an alternate to Barabbas, he eventually gives up. The crowd, under the influence of the ‘chief priests and the elders’ was so blood thirsty for Christ that they would rather choose a known criminal and murderer.
So when Pilate saw that he was gaining nothing, but rather that a riot was beginning, he took water and washed his hands before the crowd, saying, “I am innocent of this man’s blood; see to it yourselves.” (Mathew 27:24, ESV)
Conclusion: Of course Pilate had a choice, but on the other hand it is true that if he chose to ignore the blood-thirsty crowd and released Christ, as his own desire clearly indicated, it could have meant his own trouble with Caesar. Yes even loss of his position as governor, and during those days this could even possibly lead to his own death for failure to manage the people.