It's educate, AGITATE, organize
edit: putting this at the top so people understand the basis for this:
You may well ask: “Why direct action? Why sit ins, marches and so forth? Isn’t negotiation a better path?” You are quite right in calling for negotiation. Indeed, this is the very purpose of direct action. Nonviolent direct action seeks to create such a crisis and foster such a tension that a community which has constantly refused to negotiate is forced to confront the issue. It seeks so to dramatize the issue that it can no longer be ignored. My citing the creation of tension as part of the work of the nonviolent resister may sound rather shocking. But I must confess that I am not afraid of the word “tension.” I have earnestly opposed violent tension, but there is a type of constructive, nonviolent tension which is necessary for growth. Just as Socrates felt that it was necessary to create a tension in the mind so that individuals could rise from the bondage of myths and half truths to the unfettered realm of creative analysis and objective appraisal, so must we see the need for nonviolent gadflies to create the kind of tension in society that will help men rise from the dark depths of prejudice and racism to the majestic heights of understanding and brotherhood.
I'll try to clear it up a little.
Here's a recent poll showing that support for ending the invasion into Gaza isn't widely supported
There's a lot of risk to Biden's election chances if he withdraws his support for Israel, probably more risk than if he maintains his current actions. So withdrawing his support for Israel isn't the clear cut winning decision that you seem to think it is.
Your threat of withholding your vote for Joe Biden unless he changes policy to match what you want will most likely result in Joe Biden losing the election. If he changes course and withdraws support as you want then he'll probably lose more voters than he gains, costing him he election. If he stays the course and you don't vote for Joe Biden he's likely to lose the election.