(NASB) Luke 22:1-2 “NOW THE Feast of Unleavened Bread, which is called the Passover, was approaching.
2 The chief priest’s and the scribes were seeking how they might put Him to death; for they were afraid of the people.”

Public pressure is still feared by many nations’ leaders.  Public opinion polls are taken to assess what policies of various administrations are popular and/or acceptable.
The chief priests and scribes feared Jesus’ popularity and power; they also feared the people’s reaction if they killed Jesus outright.
Opposition didn’t come from only the Jewish religious leaders, betrayal came from within the twelve disciples…and Jesus was not surprised. (See Mark 14:18).

(NASB) Luke 22:3-5 “And Satan entered into Judas who was called Iscariot, belonging to the number of the twelve.
4 And he went away and discussed with the chief priests and officers how he might betray Him to them.
5 They were glad and agreed to give him money.”

Betrayers seek financial gain…greed and disillusionment will seek to betray one’s country, leaders and even friends…for money and possibly power.

(NASB) Luke 22:6 “So he consented, and began seeking a good opportunity to betray Him to them apart from the crowd.”

Betrayal looks for opportunities that will be least harmful to the betrayer.

Jesus was not caught unaware; He knew He would be betrayed.  However, He was protected from being killed in any way apart from crucifixion and at a specific time and on a specific day.
Jesus would suffer death on the altar of the cross at the time of the evening sacrifice on Passover…God’s timing, not the timing of men!

(Amplified) 1 Corinthians 5:7
“…for Christ, our Passover [Lamb], has been sacrificed.”