John 6.37: All that the Father gives me will come to me, and whoever comes to me I will never drive away.
Jesus does not try to make sense or explain two very different teachings. Election and human responsibility in salvation sit comfortably side by side in the world of Jesus.
One truth is that God chooses all who come to Him - all that the Father gives me will come to me. What else could Jesus be saying other than the Father chooses those who come to Him and in response, they will come? John says something similar in 1 John 4.10: This is love: not that we loved God, but that he loved us and sent his Son as an atoning sacrifice (propitiation) for our sins.
The second truth is we are to come to Jesus - whoever comes to me I will never drive away. Jesus never says - wait until you know if you have been called. Instead he invites all to come to him (earlier he has explained this is done through faith - John 6.12) and he will not send any away. What a great welcome and promise to come to him!
Election and human responsibility stand side by side is the words of Jesus. God sending (election) is incomplete without man coming (human responsibility) and man coming (human responsibility) will never take place without God sending (election). Jesus does not explain but simply allows us to embrace these two Biblical truths.
Now we may say, I want nothing to do with election. Salvation, in its final form, is my "sovereign" choice. But if we move further down in the passage, we once again see divine work and human responsibility standing side by side.
Divine work is shown in John 12.39: And it is the will of him who sent me, that I shall lose none of all that he has given me, but raise them up on that last day. Who would deny this great truth of God's sovereign protection? Imagine the comfort ripped out of the hearts of believers if we say - well, you know, God doesn't have the right to be that "sovereign" in my life - it is my choice. No - God will keep his people.
But following this verse is human responsibility: For my Father's will is that everyone who looks to the Son and believes in him shall have eternal life, and I will raise him up at the last day. Amazing. In order to be kept, we must believe. We must look to Jesus so we may have everlasting life.
God's sovereign grace and keeping stand alongside human responsibility - they are neither separated nor explained by Jesus. Rather, they are simply stated so God may receive all the glory and we may rejoice in the promises of everlasting life and protection offered by Jesus.